diff --git a/csharp/src/AddressBook/Addressbook.cs b/csharp/src/AddressBook/Addressbook.cs
index f55800e6d0..92f983e7c7 100644
--- a/csharp/src/AddressBook/Addressbook.cs
+++ b/csharp/src/AddressBook/Addressbook.cs
@@ -54,9 +54,6 @@ namespace Google.Protobuf.Examples.AddressBook {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Person() {
       OnConstruction();
     }
@@ -240,9 +237,6 @@ namespace Google.Protobuf.Examples.AddressBook {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public PhoneNumber() {
           OnConstruction();
         }
@@ -380,9 +374,6 @@ namespace Google.Protobuf.Examples.AddressBook {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public AddressBook() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs
index 2c87943ffc..aac30cebdb 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/MapUnittestProto3.cs
@@ -183,9 +183,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestMap() {
       OnConstruction();
     }
@@ -572,9 +569,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestMapSubmessage() {
       OnConstruction();
     }
@@ -687,9 +681,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestMessageMap() {
       OnConstruction();
     }
@@ -788,9 +779,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestSameTypeMap() {
       OnConstruction();
     }
@@ -907,9 +895,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestArenaMap() {
       OnConstruction();
     }
@@ -1260,9 +1245,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MessageContainingEnumCalledType() {
       OnConstruction();
     }
@@ -1371,9 +1353,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MessageContainingMapCalledEntry() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs
index 07ed125d41..fae1095750 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportProto3.cs
@@ -62,9 +62,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public ImportMessage() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs
index 71403fbb1c..17689f43d7 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestImportPublicProto3.cs
@@ -48,9 +48,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public PublicImportMessage() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
index f09d6769f6..1a7b9dfdcf 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
@@ -80,9 +80,6 @@ namespace UnitTest.Issues.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Issue307() {
       OnConstruction();
     }
@@ -164,9 +161,6 @@ namespace UnitTest.Issues.TestProtos {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public NestedOnce() {
           OnConstruction();
         }
@@ -248,9 +242,6 @@ namespace UnitTest.Issues.TestProtos {
               get { return Descriptor; }
             }
 
-            private bool _frozen = false;
-            public bool IsFrozen { get { return _frozen; } }
-
             public NestedTwice() {
               OnConstruction();
             }
@@ -341,9 +332,6 @@ namespace UnitTest.Issues.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public NegativeEnumMessage() {
       OnConstruction();
     }
@@ -488,9 +476,6 @@ namespace UnitTest.Issues.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public DeprecatedChild() {
       OnConstruction();
     }
@@ -571,9 +556,6 @@ namespace UnitTest.Issues.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public DeprecatedFieldsMessage() {
       OnConstruction();
     }
@@ -800,9 +782,6 @@ namespace UnitTest.Issues.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public ItemField() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
index 4d98cc25bb..1f2e9229af 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestProto3.cs
@@ -232,9 +232,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestAllTypes() {
       OnConstruction();
     }
@@ -1473,9 +1470,6 @@ namespace Google.Protobuf.TestProtos {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public NestedMessage() {
           OnConstruction();
         }
@@ -1587,9 +1581,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public NestedTestAllTypes() {
       OnConstruction();
     }
@@ -1752,9 +1743,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestDeprecatedFields() {
       OnConstruction();
     }
@@ -1862,9 +1850,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public ForeignMessage() {
       OnConstruction();
     }
@@ -1971,9 +1956,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestReservedFields() {
       OnConstruction();
     }
@@ -2054,9 +2036,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestForeignNested() {
       OnConstruction();
     }
@@ -2169,9 +2148,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestReallyLargeTagNumber() {
       OnConstruction();
     }
@@ -2304,9 +2280,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestRecursiveMessage() {
       OnConstruction();
     }
@@ -2445,9 +2418,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestMutualRecursionA() {
       OnConstruction();
     }
@@ -2560,9 +2530,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestMutualRecursionB() {
       OnConstruction();
     }
@@ -2701,9 +2668,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestCamelCaseFieldNames() {
       OnConstruction();
     }
@@ -2968,9 +2932,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestFieldOrderings() {
       OnConstruction();
     }
@@ -3162,9 +3123,6 @@ namespace Google.Protobuf.TestProtos {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public NestedMessage() {
           OnConstruction();
         }
@@ -3302,9 +3260,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public SparseEnumMessage() {
       OnConstruction();
     }
@@ -3411,9 +3366,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public OneString() {
       OnConstruction();
     }
@@ -3520,9 +3472,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MoreString() {
       OnConstruction();
     }
@@ -3621,9 +3570,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public OneBytes() {
       OnConstruction();
     }
@@ -3730,9 +3676,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MoreBytes() {
       OnConstruction();
     }
@@ -3839,9 +3782,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Int32Message() {
       OnConstruction();
     }
@@ -3948,9 +3888,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Uint32Message() {
       OnConstruction();
     }
@@ -4057,9 +3994,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Int64Message() {
       OnConstruction();
     }
@@ -4166,9 +4100,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Uint64Message() {
       OnConstruction();
     }
@@ -4275,9 +4206,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public BoolMessage() {
       OnConstruction();
     }
@@ -4384,9 +4312,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestOneof() {
       OnConstruction();
     }
@@ -4579,9 +4504,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestPackedTypes() {
       OnConstruction();
     }
@@ -4928,9 +4850,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestUnpackedTypes() {
       OnConstruction();
     }
@@ -5277,9 +5196,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestRepeatedScalarDifferentTagSizes() {
       OnConstruction();
     }
@@ -5474,9 +5390,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestCommentInjectionMessage() {
       OnConstruction();
     }
@@ -5583,9 +5496,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FooRequest() {
       OnConstruction();
     }
@@ -5666,9 +5576,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FooResponse() {
       OnConstruction();
     }
@@ -5749,9 +5656,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FooClientMessage() {
       OnConstruction();
     }
@@ -5832,9 +5736,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FooServerMessage() {
       OnConstruction();
     }
@@ -5915,9 +5816,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public BarRequest() {
       OnConstruction();
     }
@@ -5998,9 +5896,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public BarResponse() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs
index f938d70c65..f18c5f1b4b 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestWellKnownTypes.cs
@@ -183,9 +183,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public TestWellKnownTypes() {
       OnConstruction();
     }
@@ -833,9 +830,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public RepeatedWellKnownTypes() {
       OnConstruction();
     }
@@ -1240,9 +1234,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public OneofWellKnownTypes() {
       OnConstruction();
     }
@@ -1910,9 +1901,6 @@ namespace Google.Protobuf.TestProtos {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MapWellKnownTypes() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/Collections/MapField.cs b/csharp/src/Google.Protobuf/Collections/MapField.cs
index 0f7227c212..9f460e1e13 100644
--- a/csharp/src/Google.Protobuf/Collections/MapField.cs
+++ b/csharp/src/Google.Protobuf/Collections/MapField.cs
@@ -54,7 +54,6 @@ namespace Google.Protobuf.Collections
     {
         // TODO: Don't create the map/list until we have an entry. (Assume many maps will be empty.)
         private readonly bool allowNullValues;
-        private bool frozen;
         private readonly Dictionary<TKey, LinkedListNode<KeyValuePair<TKey, TValue>>> map =
             new Dictionary<TKey, LinkedListNode<KeyValuePair<TKey, TValue>>>();
         private readonly LinkedList<KeyValuePair<TKey, TValue>> list = new LinkedList<KeyValuePair<TKey, TValue>>();
@@ -254,7 +253,7 @@ namespace Google.Protobuf.Collections
         public bool AllowsNullValues { get { return allowNullValues; } }
 
         public int Count { get { return list.Count; } }
-        public bool IsReadOnly { get { return frozen; } }
+        public bool IsReadOnly { get { return false; } }
 
         public override bool Equals(object other)
         {
@@ -416,10 +415,6 @@ namespace Google.Protobuf.Collections
 
             set
             {
-                if (frozen)
-                {
-                    throw new NotSupportedException("Dictionary is frozen");
-                }
                 this[(TKey)key] = (TValue)value;
             }
         }
diff --git a/csharp/src/Google.Protobuf/Collections/RepeatedField.cs b/csharp/src/Google.Protobuf/Collections/RepeatedField.cs
index e7fc0a3f81..3ce19c819f 100644
--- a/csharp/src/Google.Protobuf/Collections/RepeatedField.cs
+++ b/csharp/src/Google.Protobuf/Collections/RepeatedField.cs
@@ -40,7 +40,7 @@ namespace Google.Protobuf.Collections
 {
     /// <summary>
     /// The contents of a repeated field: essentially, a collection with some extra
-    /// restrictions (no null values) and capabilities (deep cloning and freezing).
+    /// restrictions (no null values) and capabilities (deep cloning).
     /// </summary>
     /// <typeparam name="T">The element type of the repeated field.</typeparam>
     public sealed class RepeatedField<T> : IList<T>, IList, IDeepCloneable<RepeatedField<T>>, IEquatable<RepeatedField<T>>
@@ -48,7 +48,6 @@ namespace Google.Protobuf.Collections
         private static readonly T[] EmptyArray = new T[0];
         private const int MinArraySize = 8;
 
-        private bool frozen;
         private T[] array = EmptyArray;
         private int count = 0;
 
@@ -66,7 +65,6 @@ namespace Google.Protobuf.Collections
         public RepeatedField<T> Clone()
         {
             RepeatedField<T> clone = new RepeatedField<T>();
-            // Clone is implicitly *not* frozen, even if this object is.
             if (array != EmptyArray)
             {
                 clone.array = (T[])array.Clone();
diff --git a/csharp/src/Google.Protobuf/Reflection/DescriptorProtoFile.cs b/csharp/src/Google.Protobuf/Reflection/DescriptorProtoFile.cs
index 6f55f5ab15..213863e20c 100644
--- a/csharp/src/Google.Protobuf/Reflection/DescriptorProtoFile.cs
+++ b/csharp/src/Google.Protobuf/Reflection/DescriptorProtoFile.cs
@@ -173,9 +173,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FileDescriptorSet() {
       OnConstruction();
     }
@@ -274,9 +271,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FileDescriptorProto() {
       OnConstruction();
     }
@@ -627,9 +621,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public DescriptorProto() {
       OnConstruction();
     }
@@ -913,9 +904,6 @@ namespace Google.Protobuf.Reflection {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public ExtensionRange() {
           OnConstruction();
         }
@@ -1048,9 +1036,6 @@ namespace Google.Protobuf.Reflection {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public ReservedRange() {
           OnConstruction();
         }
@@ -1188,9 +1173,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FieldDescriptorProto() {
       OnConstruction();
     }
@@ -1544,9 +1526,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public OneofDescriptorProto() {
       OnConstruction();
     }
@@ -1653,9 +1632,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public EnumDescriptorProto() {
       OnConstruction();
     }
@@ -1812,9 +1788,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public EnumValueDescriptorProto() {
       OnConstruction();
     }
@@ -1979,9 +1952,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public ServiceDescriptorProto() {
       OnConstruction();
     }
@@ -2138,9 +2108,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MethodDescriptorProto() {
       OnConstruction();
     }
@@ -2383,9 +2350,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FileOptions() {
       OnConstruction();
     }
@@ -2860,9 +2824,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MessageOptions() {
       OnConstruction();
     }
@@ -3065,9 +3026,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FieldOptions() {
       OnConstruction();
     }
@@ -3340,9 +3298,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public EnumOptions() {
       OnConstruction();
     }
@@ -3493,9 +3448,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public EnumValueOptions() {
       OnConstruction();
     }
@@ -3620,9 +3572,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public ServiceOptions() {
       OnConstruction();
     }
@@ -3747,9 +3696,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public MethodOptions() {
       OnConstruction();
     }
@@ -3874,9 +3820,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public UninterpretedOption() {
       OnConstruction();
     }
@@ -4132,9 +4075,6 @@ namespace Google.Protobuf.Reflection {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public NamePart() {
           OnConstruction();
         }
@@ -4272,9 +4212,6 @@ namespace Google.Protobuf.Reflection {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public SourceCodeInfo() {
       OnConstruction();
     }
@@ -4374,9 +4311,6 @@ namespace Google.Protobuf.Reflection {
           get { return Descriptor; }
         }
 
-        private bool _frozen = false;
-        public bool IsFrozen { get { return _frozen; } }
-
         public Location() {
           OnConstruction();
         }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
index 7882b991de..86c8552fef 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Any.cs
@@ -51,9 +51,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Any() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
index a066fd51c0..a8d4942a4e 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Api.cs
@@ -61,9 +61,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Api() {
       OnConstruction();
     }
@@ -264,9 +261,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Method() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
index 3c43d6341c..26c8d2b6c0 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Duration.cs
@@ -52,9 +52,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Duration() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
index f310440927..e14992f453 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Empty.cs
@@ -51,9 +51,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Empty() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
index c090aae870..45ef9859b8 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/FieldMask.cs
@@ -51,9 +51,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FieldMask() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs b/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
index 73874cf1ee..c86dbadaa1 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/SourceContext.cs
@@ -52,9 +52,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public SourceContext() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
index bb2e5c1bfa..a4411dd010 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Struct.cs
@@ -70,9 +70,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Struct() {
       OnConstruction();
     }
@@ -171,9 +168,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Value() {
       OnConstruction();
     }
@@ -459,9 +453,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public ListValue() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
index f66b1f43cc..3c42068ab3 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Timestamp.cs
@@ -52,9 +52,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Timestamp() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
index 719131a48e..91ac0f6b10 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Type.cs
@@ -82,9 +82,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Type() {
       OnConstruction();
     }
@@ -277,9 +274,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Field() {
       OnConstruction();
     }
@@ -594,9 +588,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Enum() {
       OnConstruction();
     }
@@ -771,9 +762,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public EnumValue() {
       OnConstruction();
     }
@@ -924,9 +912,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Option() {
       OnConstruction();
     }
diff --git a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
index 73577366ec..a5f6b7e8d4 100644
--- a/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
+++ b/csharp/src/Google.Protobuf/WellKnownTypes/Wrappers.cs
@@ -61,9 +61,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public DoubleValue() {
       OnConstruction();
     }
@@ -170,9 +167,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public FloatValue() {
       OnConstruction();
     }
@@ -279,9 +273,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Int64Value() {
       OnConstruction();
     }
@@ -388,9 +379,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public UInt64Value() {
       OnConstruction();
     }
@@ -497,9 +485,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public Int32Value() {
       OnConstruction();
     }
@@ -606,9 +591,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public UInt32Value() {
       OnConstruction();
     }
@@ -715,9 +697,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public BoolValue() {
       OnConstruction();
     }
@@ -824,9 +803,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public StringValue() {
       OnConstruction();
     }
@@ -933,9 +909,6 @@ namespace Google.Protobuf.WellKnownTypes {
       get { return Descriptor; }
     }
 
-    private bool _frozen = false;
-    public bool IsFrozen { get { return _frozen; } }
-
     public BytesValue() {
       OnConstruction();
     }
diff --git a/src/google/protobuf/compiler/csharp/csharp_message.cc b/src/google/protobuf/compiler/csharp/csharp_message.cc
index 86ef0489e2..54e7d92db7 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_message.cc
@@ -134,9 +134,7 @@ void MessageGenerator::Generate(io::Printer* printer) {
     "pbr::MessageDescriptor pb::IMessage.Descriptor {\n"
     "  get { return Descriptor; }\n"
     "}\n"
-    "\n"
-    "private bool _frozen = false;\n"
-    "public bool IsFrozen { get { return _frozen; } }\n\n");
+    "\n");
 
   // Parameterless constructor and partial OnConstruction method.
   printer->Print(