diff --git a/Makefile.am b/Makefile.am
index c8e730f94e..3c0cea5ac5 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -99,7 +99,6 @@ csharp_EXTRA_DIST=                                                           \
   csharp/src/Google.Protobuf/Collections/RepeatedField.cs                    \
   csharp/src/Google.Protobuf/FieldCodec.cs                                   \
   csharp/src/Google.Protobuf/FrameworkPortability.cs                         \
-  csharp/src/Google.Protobuf/Freezable.cs                                    \
   csharp/src/Google.Protobuf/Google.Protobuf.csproj                          \
   csharp/src/Google.Protobuf/Google.Protobuf.nuspec                          \
   csharp/src/Google.Protobuf/IMessage.cs                                     \
diff --git a/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs b/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs
index 46d3bd9aaa..c62ac046b6 100644
--- a/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs
+++ b/csharp/src/Google.Protobuf.Test/Collections/MapFieldTest.cs
@@ -45,53 +45,6 @@ namespace Google.Protobuf.Collections
     /// </summary>
     public class MapFieldTest
     {
-        // Protobuf-specific tests
-        [Test]
-        public void Freeze_FreezesMessages()
-        {
-            var message = new ForeignMessage { C = 20 };
-            var map = new MapField<string, ForeignMessage> { { "x", message } };
-            map.Freeze();
-            Assert.IsTrue(message.IsFrozen);
-        }
-
-        [Test]
-        public void Freeze_Idempotent()
-        {
-            var message = new ForeignMessage { C = 20 };
-            var map = new MapField<string, ForeignMessage> { { "x", message } };
-            Assert.IsFalse(map.IsFrozen);
-            map.Freeze();
-            Assert.IsTrue(message.IsFrozen);
-            map.Freeze();
-            Assert.IsTrue(message.IsFrozen);
-        }
-
-        [Test]
-        public void Freeze_PreventsMutation()
-        {
-            var map = new MapField<string, string>();
-            map.Freeze();
-            Assert.IsTrue(map.IsFrozen);
-            Assert.IsTrue(map.IsReadOnly);
-            ICollection<KeyValuePair<string, string>> collection = map;
-            Assert.Throws<InvalidOperationException>(() => map["x"] = "y");
-            Assert.Throws<InvalidOperationException>(() => map.Add("x", "y"));
-            Assert.Throws<InvalidOperationException>(() => map.Remove("x"));
-            Assert.Throws<InvalidOperationException>(() => map.Clear());
-            Assert.Throws<InvalidOperationException>(() => collection.Add(NewKeyValuePair("x", "y")));
-            Assert.Throws<InvalidOperationException>(() => collection.Remove(NewKeyValuePair("x", "y")));
-        }
-
-        [Test]
-        public void Clone_ReturnsNonFrozen()
-        {
-            var map = new MapField<string, string>();
-            map.Freeze();
-            var clone = map.Clone();
-            clone.Add("x", "y");
-        }
-
         [Test]
         public void Clone_ClonesMessages()
         {
@@ -422,10 +375,6 @@ namespace Google.Protobuf.Collections
             dictionary.Remove("x");
             Assert.AreEqual(0, dictionary.Count);
             Assert.Throws<ArgumentNullException>(() => dictionary.Remove(null));
-
-            map.Freeze();
-            // Call should fail even though it clearly doesn't contain 5 as a key.
-            Assert.Throws<InvalidOperationException>(() => dictionary.Remove(5));
         }
 
         [Test]
@@ -449,8 +398,6 @@ namespace Google.Protobuf.Collections
             var map = new MapField<string, string> { { "x", "y" } };
             IDictionary dictionary = map;
             Assert.IsFalse(dictionary.IsFixedSize);
-            map.Freeze();
-            Assert.IsTrue(dictionary.IsFixedSize);
         }
 
         [Test]
@@ -504,9 +451,6 @@ namespace Google.Protobuf.Collections
             Assert.Throws<InvalidCastException>(() => dictionary["x"] = 5);
             Assert.Throws<ArgumentNullException>(() => dictionary[null] = "z");
             Assert.Throws<ArgumentNullException>(() => dictionary["x"] = null);
-            map.Freeze();
-            // Note: Not InvalidOperationException.
-            Assert.Throws<NotSupportedException>(() => dictionary["a"] = "c");
         }
 
         [Test]
diff --git a/csharp/src/Google.Protobuf.Test/Collections/RepeatedFieldTest.cs b/csharp/src/Google.Protobuf.Test/Collections/RepeatedFieldTest.cs
index 25be7731f4..33c4e10c88 100644
--- a/csharp/src/Google.Protobuf.Test/Collections/RepeatedFieldTest.cs
+++ b/csharp/src/Google.Protobuf.Test/Collections/RepeatedFieldTest.cs
@@ -193,44 +193,10 @@ namespace Google.Protobuf.Collections
             Assert.Throws<ArgumentOutOfRangeException>(() => list[2] = "bad");
         }
 
-        [Test]
-        public void Freeze_FreezesElements()
-        {
-            var list = new RepeatedField<TestAllTypes> { new TestAllTypes() };
-            Assert.IsFalse(list[0].IsFrozen);
-            list.Freeze();
-            Assert.IsTrue(list[0].IsFrozen);
-        }
-
-        [Test]
-        public void Freeze_PreventsMutations()
-        {
-            var list = new RepeatedField<int> { 0 };
-            list.Freeze();
-            Assert.Throws<InvalidOperationException>(() => list.Add(1));
-            Assert.Throws<InvalidOperationException>(() => list[0] = 1);
-            Assert.Throws<InvalidOperationException>(() => list.Clear());
-            Assert.Throws<InvalidOperationException>(() => list.RemoveAt(0));
-            Assert.Throws<InvalidOperationException>(() => list.Remove(0));
-            Assert.Throws<InvalidOperationException>(() => list.Insert(0, 0));
-        }
-
-        [Test]
-        public void Freeze_ReportsFrozen()
-        {
-            var list = new RepeatedField<int> { 0 };
-            Assert.IsFalse(list.IsFrozen);
-            Assert.IsFalse(list.IsReadOnly);
-            list.Freeze();
-            Assert.IsTrue(list.IsFrozen);
-            Assert.IsTrue(list.IsReadOnly);
-        }
-
         [Test]
         public void Clone_ReturnsMutable()
         {
             var list = new RepeatedField<int> { 0 };
-            list.Freeze();
             var clone = list.Clone();
             clone[0] = 1;
         }
@@ -585,8 +551,6 @@ namespace Google.Protobuf.Collections
             var field = new RepeatedField<string> { "first", "second" };
             IList list = field;
             Assert.IsFalse(list.IsFixedSize);
-            field.Freeze();
-            Assert.IsTrue(list.IsFixedSize);
         }
 
         [Test]
diff --git a/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs b/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
index 528a4023fc..dfaac48cd0 100644
--- a/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
+++ b/csharp/src/Google.Protobuf.Test/GeneratedMessageTest.cs
@@ -503,23 +503,6 @@ namespace Google.Protobuf
             Assert.AreNotEqual(original, clone);
         }
 
-        [Test]
-        public void Freeze()
-        {
-            var frozen = new TestAllTypes();
-            frozen.Freeze();
-            Assert.IsTrue(frozen.IsFrozen);
-
-            Assert.Throws<InvalidOperationException>(() => frozen.ClearOneofField());
-            Assert.Throws<InvalidOperationException>(() => frozen.SingleInt32 = 0);
-            Assert.Throws<InvalidOperationException>(() => frozen.SingleNestedMessage = null);
-            Assert.Throws<InvalidOperationException>(() => frozen.SingleNestedEnum = 0);
-            Assert.Throws<InvalidOperationException>(() => frozen.OneofString = null);
-            Assert.Throws<InvalidOperationException>(() => frozen.OneofUint32 = 0U);
-            Assert.Throws<InvalidOperationException>(() => frozen.RepeatedDouble.Add(0.0));
-            Assert.Throws<InvalidOperationException>(() => frozen.RepeatedNestedMessage.Add(new TestAllTypes.Types.NestedMessage()));
-        }
-
         [Test]
         public void OneofProperties()
         {
diff --git a/csharp/src/Google.Protobuf/Collections/MapField.cs b/csharp/src/Google.Protobuf/Collections/MapField.cs
index 68f2f1cc2a..0f7227c212 100644
--- a/csharp/src/Google.Protobuf/Collections/MapField.cs
+++ b/csharp/src/Google.Protobuf/Collections/MapField.cs
@@ -50,7 +50,7 @@ namespace Google.Protobuf.Collections
     /// </remarks>
     /// <typeparam name="TKey">Key type in the map. Must be a type supported by Protocol Buffer map keys.</typeparam>
     /// <typeparam name="TValue">Value type in the map. Must be a type supported by Protocol Buffers.</typeparam>
-    public sealed class MapField<TKey, TValue> : IDeepCloneable<MapField<TKey, TValue>>, IFreezable, IDictionary<TKey, TValue>, IEquatable<MapField<TKey, TValue>>, IDictionary
+    public sealed class MapField<TKey, TValue> : IDeepCloneable<MapField<TKey, TValue>>, IDictionary<TKey, TValue>, IEquatable<MapField<TKey, TValue>>, IDictionary
     {
         // TODO: Don't create the map/list until we have an entry. (Assume many maps will be empty.)
         private readonly bool allowNullValues;
@@ -119,7 +119,6 @@ namespace Google.Protobuf.Collections
 
         public bool Remove(TKey key)
         {
-            this.CheckMutable();
             ThrowHelper.ThrowIfNull(key, "key");
             LinkedListNode<KeyValuePair<TKey, TValue>> node;
             if (map.TryGetValue(key, out node))
@@ -169,7 +168,6 @@ namespace Google.Protobuf.Collections
                 {
                     ThrowHelper.ThrowIfNull(value, "value");
                 }
-                this.CheckMutable();
                 LinkedListNode<KeyValuePair<TKey, TValue>> node;
                 var pair = new KeyValuePair<TKey, TValue>(key, value);
                 if (map.TryGetValue(key, out node))
@@ -214,7 +212,6 @@ namespace Google.Protobuf.Collections
 
         public void Clear()
         {
-            this.CheckMutable();
             list.Clear();
             map.Clear();
         }
@@ -233,7 +230,6 @@ namespace Google.Protobuf.Collections
 
         bool ICollection<KeyValuePair<TKey, TValue>>.Remove(KeyValuePair<TKey, TValue> item)
         {
-            this.CheckMutable();
             if (item.Key == null)
             {
                 throw new ArgumentException("Key is null", "item");
@@ -260,31 +256,6 @@ namespace Google.Protobuf.Collections
         public int Count { get { return list.Count; } }
         public bool IsReadOnly { get { return frozen; } }
 
-        public void Freeze()
-        {
-            if (IsFrozen)
-            {
-                return;
-            }
-            frozen = true;
-            // Only values can be frozen, as all the key types are simple.
-            // Everything can be done in-place, as we're just freezing objects.
-            if (typeof(IFreezable).IsAssignableFrom(typeof(TValue)))
-            {
-                for (var node = list.First; node != null; node = node.Next)
-                {
-                    var pair = node.Value;
-                    IFreezable freezableValue = pair.Value as IFreezable;
-                    if (freezableValue != null)
-                    {
-                        freezableValue.Freeze();
-                    }
-                }
-            }
-        }
-
-        public bool IsFrozen { get { return frozen; } }
-
         public override bool Equals(object other)
         {
             return Equals(other as MapField<TKey, TValue>);
@@ -405,7 +376,6 @@ namespace Google.Protobuf.Collections
         void IDictionary.Remove(object key)
         {
             ThrowHelper.ThrowIfNull(key, "key");
-            this.CheckMutable();
             if (!(key is TKey))
             {
                 return;
@@ -420,7 +390,7 @@ namespace Google.Protobuf.Collections
             temp.CopyTo(array, index);
         }
 
-        bool IDictionary.IsFixedSize { get { return IsFrozen; } }
+        bool IDictionary.IsFixedSize { get { return false; } }
 
         ICollection IDictionary.Keys { get { return (ICollection)Keys; } }
 
diff --git a/csharp/src/Google.Protobuf/Collections/RepeatedField.cs b/csharp/src/Google.Protobuf/Collections/RepeatedField.cs
index ccd1a9bb3f..e7fc0a3f81 100644
--- a/csharp/src/Google.Protobuf/Collections/RepeatedField.cs
+++ b/csharp/src/Google.Protobuf/Collections/RepeatedField.cs
@@ -43,7 +43,7 @@ namespace Google.Protobuf.Collections
     /// restrictions (no null values) and capabilities (deep cloning and freezing).
     /// </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>>, IFreezable
+    public sealed class RepeatedField<T> : IList<T>, IList, IDeepCloneable<RepeatedField<T>>, IEquatable<RepeatedField<T>>
     {
         private static readonly T[] EmptyArray = new T[0];
         private const int MinArraySize = 8;
@@ -190,21 +190,6 @@ namespace Google.Protobuf.Collections
             }
         }
 
-        public bool IsFrozen { get { return frozen; } }
-
-        public void Freeze()
-        {
-            frozen = true;
-            IFreezable[] freezableArray = array as IFreezable[];
-            if (freezableArray != null)
-            {
-                for (int i = 0; i < count; i++)
-                {
-                    freezableArray[i].Freeze();
-                }
-            }
-        }
-
         private void EnsureSize(int size)
         {
             if (array.Length < size)
@@ -223,14 +208,12 @@ namespace Google.Protobuf.Collections
             {
                 throw new ArgumentNullException("item");
             }
-            this.CheckMutable();
             EnsureSize(count + 1);
             array[count++] = item;
         }
 
         public void Clear()
         {
-            this.CheckMutable();
             array = EmptyArray;
             count = 0;
         }
@@ -247,7 +230,6 @@ namespace Google.Protobuf.Collections
 
         public bool Remove(T item)
         {
-            this.CheckMutable();
             int index = IndexOf(item);
             if (index == -1)
             {
@@ -261,7 +243,7 @@ namespace Google.Protobuf.Collections
 
         public int Count { get { return count; } }
 
-        public bool IsReadOnly { get { return IsFrozen; } }
+        public bool IsReadOnly { get { return false; } }
 
         public void Add(RepeatedField<T> values)
         {
@@ -269,7 +251,6 @@ namespace Google.Protobuf.Collections
             {
                 throw new ArgumentNullException("values");
             }
-            this.CheckMutable();
             EnsureSize(count + values.count);
             // We know that all the values will be valid, because it's a RepeatedField.
             Array.Copy(values.array, 0, array, count, values.count);
@@ -282,7 +263,6 @@ namespace Google.Protobuf.Collections
             {
                 throw new ArgumentNullException("values");
             }
-            this.CheckMutable();
             // TODO: Check for ICollection and get the Count?
             foreach (T item in values)
             {
@@ -372,7 +352,6 @@ namespace Google.Protobuf.Collections
             {
                 throw new ArgumentOutOfRangeException("index");
             }
-            this.CheckMutable();
             EnsureSize(count + 1);
             Array.Copy(array, index, array, index + 1, count - index);
             array[index] = item;
@@ -385,7 +364,6 @@ namespace Google.Protobuf.Collections
             {
                 throw new ArgumentOutOfRangeException("index");
             }
-            this.CheckMutable();
             Array.Copy(array, index + 1, array, index, count - index - 1);
             count--;
             array[count] = default(T);
@@ -407,7 +385,6 @@ namespace Google.Protobuf.Collections
                 {
                     throw new ArgumentOutOfRangeException("index");
                 }
-                this.CheckMutable();
                 if (value == null)
                 {
                     throw new ArgumentNullException("value");
@@ -417,7 +394,7 @@ namespace Google.Protobuf.Collections
         }
 
         #region Explicit interface implementation for IList and ICollection.
-        bool IList.IsFixedSize { get { return IsFrozen; } }
+        bool IList.IsFixedSize { get { return false; } }
 
         void ICollection.CopyTo(Array array, int index)
         {
diff --git a/csharp/src/Google.Protobuf/Freezable.cs b/csharp/src/Google.Protobuf/Freezable.cs
deleted file mode 100644
index d16e1b4272..0000000000
--- a/csharp/src/Google.Protobuf/Freezable.cs
+++ /dev/null
@@ -1,58 +0,0 @@
-#region Copyright notice and license
-// Protocol Buffers - Google's data interchange format
-// Copyright 2015 Google Inc.  All rights reserved.
-// https://developers.google.com/protocol-buffers/
-//
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-// notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-// copyright notice, this list of conditions and the following disclaimer
-// in the documentation and/or other materials provided with the
-// distribution.
-//     * Neither the name of Google Inc. nor the names of its
-// contributors may be used to endorse or promote products derived from
-// this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-#endregion
-
-using System;
-
-namespace Google.Protobuf
-{
-    /// <summary>
-    /// Extension methods for <see cref="IFreezable"/> types.
-    /// </summary>
-    public static class Freezable
-    {
-        /// <summary>
-        /// Throws an <see cref="InvalidOperationException"/> if <paramref name="target"/>
-        /// is frozen.
-        /// </summary>
-        /// <remarks>
-        /// This is a convenience methods that freezable types can call before all
-        /// mutations, to protect frozen objects.
-        /// </remarks>
-        public static void CheckMutable(this IFreezable target)
-        {
-            if (target.IsFrozen)
-            {
-                throw new InvalidOperationException("Attempt to mutate frozen object");
-            }
-        }
-    }
-}
diff --git a/csharp/src/Google.Protobuf/Google.Protobuf.csproj b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
index b1f20816da..b141e4342c 100644
--- a/csharp/src/Google.Protobuf/Google.Protobuf.csproj
+++ b/csharp/src/Google.Protobuf/Google.Protobuf.csproj
@@ -64,7 +64,6 @@
     <Compile Include="Compatibility\TypeExtensions.cs" />
     <Compile Include="FieldCodec.cs" />
     <Compile Include="FrameworkPortability.cs" />
-    <Compile Include="Freezable.cs" />
     <Compile Include="JsonFormatter.cs" />
     <Compile Include="MessageExtensions.cs" />
     <Compile Include="IMessage.cs" />
diff --git a/csharp/src/Google.Protobuf/IMessage.cs b/csharp/src/Google.Protobuf/IMessage.cs
index d179c38607..60c6f8c317 100644
--- a/csharp/src/Google.Protobuf/IMessage.cs
+++ b/csharp/src/Google.Protobuf/IMessage.cs
@@ -79,7 +79,7 @@ namespace Google.Protobuf
     /// the implementation class.
     /// </summary>
     /// <typeparam name="T">The message type.</typeparam>
-    public interface IMessage<T> : IMessage, IEquatable<T>, IDeepCloneable<T>, IFreezable where T : IMessage<T>
+    public interface IMessage<T> : IMessage, IEquatable<T>, IDeepCloneable<T> where T : IMessage<T>
     {
         /// <summary>
         /// Merges the given message into this one.
@@ -97,10 +97,6 @@ namespace Google.Protobuf
     /// Additionally, due to the type constraint on <c>T</c> in <see cref="IMessage{T}"/>,
     /// it is simpler to keep this as a separate interface.
     /// </para>
-    /// <para>
-    /// Freezable types which implement this interface should always return a mutable clone,
-    /// even if the original object is frozen.
-    /// </para>
     /// </remarks>
     /// <typeparam name="T">The type itself, returned by the <see cref="Clone"/> method.</typeparam>
     public interface IDeepCloneable<T>
@@ -111,32 +107,4 @@ namespace Google.Protobuf
         /// <returns>A deep clone of this object.</returns>
         T Clone();
     }
-
-    /// <summary>
-    /// Provides a mechanism for freezing a message (or repeated field collection)
-    /// to make it immutable.
-    /// </summary>
-    /// <remarks>
-    /// Implementations are under no obligation to make this thread-safe: if a freezable
-    /// type instance is shared between threads before being frozen, and one thread then
-    /// freezes it, it is possible for other threads to make changes during the freezing
-    /// operation and also to observe stale values for mutated fields. Objects should be
-    /// frozen before being made available to other threads.
-    /// </remarks>
-    public interface IFreezable
-    {
-        /// <summary>
-        /// Freezes this object.
-        /// </summary>
-        /// <remarks>
-        /// If the object is already frozen, this method has no effect.
-        /// </remarks>
-        void Freeze();
-
-        /// <summary>
-        /// Returns whether or not this object is frozen (and therefore immutable).
-        /// </summary>
-        /// <value><c>true</c> if this object is frozen; <c>false</c> otherwise.</value>
-        bool IsFrozen { get; }
-    }
 }
diff --git a/src/google/protobuf/compiler/csharp/csharp_map_field.cc b/src/google/protobuf/compiler/csharp/csharp_map_field.cc
index cba24a59a3..f84ad6f7ac 100644
--- a/src/google/protobuf/compiler/csharp/csharp_map_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_map_field.cc
@@ -129,8 +129,6 @@ void MapFieldGenerator::GenerateCloningCode(io::Printer* printer) {
 }
 
 void MapFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
-  printer->Print(variables_,
-    "$name$_.Freeze();\n");
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_message.cc b/src/google/protobuf/compiler/csharp/csharp_message.cc
index 81d6274174..86ef0489e2 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_message.cc
@@ -190,7 +190,6 @@ void MessageGenerator::Generate(io::Printer* printer) {
       "  get { return $name$Case_; }\n"
       "}\n\n"
       "public void Clear$property_name$() {\n"
-      "  pb::Freezable.CheckMutable(this);\n"
       "  $name$Case_ = $property_name$OneofCase.None;\n"
       "  $name$_ = null;\n"
       "}\n\n");
@@ -293,33 +292,6 @@ void MessageGenerator::GenerateCloningCode(io::Printer* printer) {
 }
 
 void MessageGenerator::GenerateFreezingCode(io::Printer* printer) {
-    map<string, string> vars;
-    vars["class_name"] = class_name();
-    printer->Print(
-      "public void Freeze() {\n"
-      "  if (IsFrozen) {\n"
-      "    return;\n"
-      "  }\n"
-      "  _frozen = true;\n");
-    printer->Indent();
-    // Freeze non-oneof fields first (only messages and repeated fields will actually generate any code)
-    for (int i = 0; i < descriptor_->field_count(); i++) {
-        if (!descriptor_->field(i)->containing_oneof()) {
-            scoped_ptr<FieldGeneratorBase> generator(
-                CreateFieldGeneratorInternal(descriptor_->field(i)));
-            generator->GenerateFreezingCode(printer);
-        }
-    }
-
-    // For each oneof, if the value is freezable, freeze it. We don't actually need to know which type it was.
-    for (int i = 0; i < descriptor_->oneof_decl_count(); ++i) {
-        vars["name"] = UnderscoresToCamelCase(descriptor_->oneof_decl(i)->name(), false);
-        printer->Print(vars,
-            "if ($name$_ is IFreezable) ((IFreezable) $name$_).Freeze();\n");
-    }
-
-    printer->Outdent();
-    printer->Print("}\n\n");
 }
 
 void MessageGenerator::GenerateFrameworkMethods(io::Printer* printer) {
diff --git a/src/google/protobuf/compiler/csharp/csharp_message_field.cc b/src/google/protobuf/compiler/csharp/csharp_message_field.cc
index d2c3a88b48..4f576cd1f6 100644
--- a/src/google/protobuf/compiler/csharp/csharp_message_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_message_field.cc
@@ -67,7 +67,6 @@ void MessageFieldGenerator::GenerateMembers(io::Printer* printer) {
     "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $name$_; }\n"
     "  set {\n"
-    "    pb::Freezable.CheckMutable(this);\n"
     "    $name$_ = value;\n"
     "  }\n"
     "}\n");
@@ -134,8 +133,6 @@ void MessageFieldGenerator::GenerateCloningCode(io::Printer* printer) {
 }
 
 void MessageFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
-  printer->Print(variables_,
-    "if ($has_property_check$) $property_name$.Freeze();\n");
 }
 
 void MessageFieldGenerator::GenerateCodecCode(io::Printer* printer) {
@@ -161,7 +158,6 @@ void MessageOneofFieldGenerator::GenerateMembers(io::Printer* printer) {
     "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $has_property_check$ ? ($type_name$) $oneof_name$_ : null; }\n"
     "  set {\n"
-    "    pb::Freezable.CheckMutable(this);\n"
     "    $oneof_name$_ = value;\n"
     "    $oneof_name$Case_ = value == null ? $oneof_property_name$OneofCase.None : $oneof_property_name$OneofCase.$property_name$;\n"
     "  }\n"
diff --git a/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc b/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
index 4454ef029f..80f4a92d02 100644
--- a/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_primitive_field.cc
@@ -73,8 +73,7 @@ void PrimitiveFieldGenerator::GenerateMembers(io::Printer* printer) {
     variables_,
     "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $name$_; }\n"
-    "  set {\n"
-    "    pb::Freezable.CheckMutable(this);\n");
+    "  set {\n");
   if (is_value_type) {
     printer->Print(
       variables_,
@@ -176,8 +175,7 @@ void PrimitiveOneofFieldGenerator::GenerateMembers(io::Printer* printer) {
     variables_,
     "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $has_property_check$ ? ($type_name$) $oneof_name$_ : $default_value$; }\n"
-    "  set {\n"
-    "    pb::Freezable.CheckMutable(this);\n");
+    "  set {\n");
     if (is_value_type) {
       printer->Print(
         variables_,
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
index c1b29e2b6c..625631dfc8 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_enum_field.cc
@@ -117,8 +117,6 @@ void RepeatedEnumFieldGenerator::GenerateCloningCode(io::Printer* printer) {
 }
 
 void RepeatedEnumFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
-  printer->Print(variables_,
-    "$name$_.Freeze();\n");
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc b/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc
index d939fc7983..7fbab681fb 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_message_field.cc
@@ -132,8 +132,6 @@ void RepeatedMessageFieldGenerator::GenerateCloningCode(io::Printer* printer) {
 }
 
 void RepeatedMessageFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
-  printer->Print(variables_,
-    "$name$_.Freeze();\n");
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc b/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc
index 5b5d9b3d9b..1163ce73d4 100644
--- a/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_repeated_primitive_field.cc
@@ -115,8 +115,6 @@ void RepeatedPrimitiveFieldGenerator::GenerateCloningCode(io::Printer* printer)
 }
 
 void RepeatedPrimitiveFieldGenerator::GenerateFreezingCode(io::Printer* printer) {
-  printer->Print(variables_,
-    "$name$_.Freeze();\n");
 }
 
 }  // namespace csharp
diff --git a/src/google/protobuf/compiler/csharp/csharp_wrapper_field.cc b/src/google/protobuf/compiler/csharp/csharp_wrapper_field.cc
index 75ef5e50c2..44f832bfca 100644
--- a/src/google/protobuf/compiler/csharp/csharp_wrapper_field.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_wrapper_field.cc
@@ -76,7 +76,6 @@ void WrapperFieldGenerator::GenerateMembers(io::Printer* printer) {
     "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $name$_; }\n"
     "  set {\n"
-    "    pb::Freezable.CheckMutable(this);\n"
     "    $name$_ = value;\n"
     "  }\n"
     "}\n");
@@ -172,7 +171,6 @@ void WrapperOneofFieldGenerator::GenerateMembers(io::Printer* printer) {
     "$access_level$ $type_name$ $property_name$ {\n"
     "  get { return $has_property_check$ ? ($type_name$) $oneof_name$_ : ($type_name$) null; }\n"
     "  set {\n"
-    "    pb::Freezable.CheckMutable(this);\n"
     "    $oneof_name$_ = value;\n"
     "    $oneof_name$Case_ = value == null ? $oneof_property_name$OneofCase.None : $oneof_property_name$OneofCase.$property_name$;\n"
     "  }\n"