diff --git a/csharp/protos/extest/unittest_issues.proto b/csharp/protos/extest/unittest_issues.proto
index 33ce7d9bd3..b0c92fa2f3 100644
--- a/csharp/protos/extest/unittest_issues.proto
+++ b/csharp/protos/extest/unittest_issues.proto
@@ -80,3 +80,12 @@ message DeprecatedFieldsMessage {
 message ItemField {
   int32 item = 1;
 }
+
+message ReservedNames {
+  // Force a nested type called Types
+  message SomeNestedType {
+  }
+
+  int32 types = 1;
+  int32 descriptor = 2;
+}
\ No newline at end of file
diff --git a/csharp/src/Google.Protobuf.Test/IssuesTest.cs b/csharp/src/Google.Protobuf.Test/IssuesTest.cs
index b5ad34ae3d..47a10c5066 100644
--- a/csharp/src/Google.Protobuf.Test/IssuesTest.cs
+++ b/csharp/src/Google.Protobuf.Test/IssuesTest.cs
@@ -52,5 +52,13 @@ namespace Google.Protobuf
             // TODO(jonskeet): Reflection...
             // Assert.AreEqual(3, (int)message[field]);
         }
+
+        [Test]
+        public void ReservedNames()
+        {
+            var message = new ReservedNames { Types_ = 10, Descriptor_ = 20 };
+            // Underscores aren't reflected in the JSON.
+            Assert.AreEqual("{ \"types\": 10, \"descriptor\": 20 }", message.ToString());
+        }
     }
 }
diff --git a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
index 1a7b9dfdcf..92485c51fe 100644
--- a/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
+++ b/csharp/src/Google.Protobuf.Test/TestProtos/UnittestIssues.cs
@@ -34,11 +34,13 @@ namespace UnitTest.Issues.TestProtos {
             "aXR0ZXN0X2lzc3Vlcy5EZXByZWNhdGVkQ2hpbGRCAhgBEjYKCUVudW1WYWx1", 
             "ZRgFIAEoDjIfLnVuaXR0ZXN0X2lzc3Vlcy5EZXByZWNhdGVkRW51bUICGAES", 
             "NgoJRW51bUFycmF5GAYgAygOMh8udW5pdHRlc3RfaXNzdWVzLkRlcHJlY2F0", 
-            "ZWRFbnVtQgIYASIZCglJdGVtRmllbGQSDAoEaXRlbRgBIAEoBSpVCgxOZWdh", 
-            "dGl2ZUVudW0SFgoSTkVHQVRJVkVfRU5VTV9aRVJPEAASFgoJRml2ZUJlbG93", 
-            "EPv//////////wESFQoITWludXNPbmUQ////////////ASouCg5EZXByZWNh", 
-            "dGVkRW51bRITCg9ERVBSRUNBVEVEX1pFUk8QABIHCgNvbmUQAUIfSAGqAhpV", 
-            "bml0VGVzdC5Jc3N1ZXMuVGVzdFByb3Rvc2IGcHJvdG8z"));
+            "ZWRFbnVtQgIYASIZCglJdGVtRmllbGQSDAoEaXRlbRgBIAEoBSJECg1SZXNl", 
+            "cnZlZE5hbWVzEg0KBXR5cGVzGAEgASgFEhIKCmRlc2NyaXB0b3IYAiABKAUa", 
+            "EAoOU29tZU5lc3RlZFR5cGUqVQoMTmVnYXRpdmVFbnVtEhYKEk5FR0FUSVZF", 
+            "X0VOVU1fWkVSTxAAEhYKCUZpdmVCZWxvdxD7//////////8BEhUKCE1pbnVz", 
+            "T25lEP///////////wEqLgoORGVwcmVjYXRlZEVudW0SEwoPREVQUkVDQVRF", 
+            "RF9aRVJPEAASBwoDb25lEAFCH0gBqgIaVW5pdFRlc3QuSXNzdWVzLlRlc3RQ", 
+            "cm90b3NiBnByb3RvMw=="));
       descriptor = pbr::FileDescriptor.InternalBuildGeneratedFileFrom(descriptorData,
           new pbr::FileDescriptor[] { },
           new pbr::GeneratedCodeInfo(new[] {typeof(global::UnitTest.Issues.TestProtos.NegativeEnum), typeof(global::UnitTest.Issues.TestProtos.DeprecatedEnum), }, new pbr::GeneratedCodeInfo[] {
@@ -46,7 +48,8 @@ namespace UnitTest.Issues.TestProtos {
             new pbr::GeneratedCodeInfo(typeof(global::UnitTest.Issues.TestProtos.NegativeEnumMessage), new[]{ "Value", "Values", "PackedValues" }, null, null, null),
             new pbr::GeneratedCodeInfo(typeof(global::UnitTest.Issues.TestProtos.DeprecatedChild), null, null, null, null),
             new pbr::GeneratedCodeInfo(typeof(global::UnitTest.Issues.TestProtos.DeprecatedFieldsMessage), new[]{ "PrimitiveValue", "PrimitiveArray", "MessageValue", "MessageArray", "EnumValue", "EnumArray" }, null, null, null),
-            new pbr::GeneratedCodeInfo(typeof(global::UnitTest.Issues.TestProtos.ItemField), new[]{ "Item" }, null, null, null)
+            new pbr::GeneratedCodeInfo(typeof(global::UnitTest.Issues.TestProtos.ItemField), new[]{ "Item" }, null, null, null),
+            new pbr::GeneratedCodeInfo(typeof(global::UnitTest.Issues.TestProtos.ReservedNames), new[]{ "Types_", "Descriptor_" }, null, null, new pbr::GeneratedCodeInfo[] { new pbr::GeneratedCodeInfo(typeof(global::UnitTest.Issues.TestProtos.ReservedNames.Types.SomeNestedType), null, null, null, null)})
           }));
     }
     #endregion
@@ -875,6 +878,224 @@ namespace UnitTest.Issues.TestProtos {
 
   }
 
+  [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+  public sealed partial class ReservedNames : pb::IMessage<ReservedNames> {
+    private static readonly pb::MessageParser<ReservedNames> _parser = new pb::MessageParser<ReservedNames>(() => new ReservedNames());
+    public static pb::MessageParser<ReservedNames> Parser { get { return _parser; } }
+
+    public static pbr::MessageDescriptor Descriptor {
+      get { return global::UnitTest.Issues.TestProtos.UnittestIssues.Descriptor.MessageTypes[5]; }
+    }
+
+    pbr::MessageDescriptor pb::IMessage.Descriptor {
+      get { return Descriptor; }
+    }
+
+    public ReservedNames() {
+      OnConstruction();
+    }
+
+    partial void OnConstruction();
+
+    public ReservedNames(ReservedNames other) : this() {
+      types_ = other.types_;
+      descriptor_ = other.descriptor_;
+    }
+
+    public ReservedNames Clone() {
+      return new ReservedNames(this);
+    }
+
+    public const int Types_FieldNumber = 1;
+    private int types_;
+    public int Types_ {
+      get { return types_; }
+      set {
+        types_ = value;
+      }
+    }
+
+    public const int Descriptor_FieldNumber = 2;
+    private int descriptor_;
+    public int Descriptor_ {
+      get { return descriptor_; }
+      set {
+        descriptor_ = value;
+      }
+    }
+
+    public override bool Equals(object other) {
+      return Equals(other as ReservedNames);
+    }
+
+    public bool Equals(ReservedNames other) {
+      if (ReferenceEquals(other, null)) {
+        return false;
+      }
+      if (ReferenceEquals(other, this)) {
+        return true;
+      }
+      if (Types_ != other.Types_) return false;
+      if (Descriptor_ != other.Descriptor_) return false;
+      return true;
+    }
+
+    public override int GetHashCode() {
+      int hash = 1;
+      if (Types_ != 0) hash ^= Types_.GetHashCode();
+      if (Descriptor_ != 0) hash ^= Descriptor_.GetHashCode();
+      return hash;
+    }
+
+    public override string ToString() {
+      return pb::JsonFormatter.Default.Format(this);
+    }
+
+    public void WriteTo(pb::CodedOutputStream output) {
+      if (Types_ != 0) {
+        output.WriteRawTag(8);
+        output.WriteInt32(Types_);
+      }
+      if (Descriptor_ != 0) {
+        output.WriteRawTag(16);
+        output.WriteInt32(Descriptor_);
+      }
+    }
+
+    public int CalculateSize() {
+      int size = 0;
+      if (Types_ != 0) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(Types_);
+      }
+      if (Descriptor_ != 0) {
+        size += 1 + pb::CodedOutputStream.ComputeInt32Size(Descriptor_);
+      }
+      return size;
+    }
+
+    public void MergeFrom(ReservedNames other) {
+      if (other == null) {
+        return;
+      }
+      if (other.Types_ != 0) {
+        Types_ = other.Types_;
+      }
+      if (other.Descriptor_ != 0) {
+        Descriptor_ = other.Descriptor_;
+      }
+    }
+
+    public void MergeFrom(pb::CodedInputStream input) {
+      uint tag;
+      while (input.ReadTag(out tag)) {
+        switch(tag) {
+          case 0:
+            throw pb::InvalidProtocolBufferException.InvalidTag();
+          default:
+            if (pb::WireFormat.IsEndGroupTag(tag)) {
+              return;
+            }
+            break;
+          case 8: {
+            Types_ = input.ReadInt32();
+            break;
+          }
+          case 16: {
+            Descriptor_ = input.ReadInt32();
+            break;
+          }
+        }
+      }
+    }
+
+    #region Nested types
+    [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+    public static partial class Types {
+      [global::System.Diagnostics.DebuggerNonUserCodeAttribute()]
+      public sealed partial class SomeNestedType : pb::IMessage<SomeNestedType> {
+        private static readonly pb::MessageParser<SomeNestedType> _parser = new pb::MessageParser<SomeNestedType>(() => new SomeNestedType());
+        public static pb::MessageParser<SomeNestedType> Parser { get { return _parser; } }
+
+        public static pbr::MessageDescriptor Descriptor {
+          get { return global::UnitTest.Issues.TestProtos.ReservedNames.Descriptor.NestedTypes[0]; }
+        }
+
+        pbr::MessageDescriptor pb::IMessage.Descriptor {
+          get { return Descriptor; }
+        }
+
+        public SomeNestedType() {
+          OnConstruction();
+        }
+
+        partial void OnConstruction();
+
+        public SomeNestedType(SomeNestedType other) : this() {
+        }
+
+        public SomeNestedType Clone() {
+          return new SomeNestedType(this);
+        }
+
+        public override bool Equals(object other) {
+          return Equals(other as SomeNestedType);
+        }
+
+        public bool Equals(SomeNestedType other) {
+          if (ReferenceEquals(other, null)) {
+            return false;
+          }
+          if (ReferenceEquals(other, this)) {
+            return true;
+          }
+          return true;
+        }
+
+        public override int GetHashCode() {
+          int hash = 1;
+          return hash;
+        }
+
+        public override string ToString() {
+          return pb::JsonFormatter.Default.Format(this);
+        }
+
+        public void WriteTo(pb::CodedOutputStream output) {
+        }
+
+        public int CalculateSize() {
+          int size = 0;
+          return size;
+        }
+
+        public void MergeFrom(SomeNestedType other) {
+          if (other == null) {
+            return;
+          }
+        }
+
+        public void MergeFrom(pb::CodedInputStream input) {
+          uint tag;
+          while (input.ReadTag(out tag)) {
+            switch(tag) {
+              case 0:
+                throw pb::InvalidProtocolBufferException.InvalidTag();
+              default:
+                if (pb::WireFormat.IsEndGroupTag(tag)) {
+                  return;
+                }
+                break;
+            }
+          }
+        }
+
+      }
+
+    }
+    #endregion
+
+  }
+
   #endregion
 
 }
diff --git a/src/google/protobuf/compiler/csharp/csharp_helpers.cc b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
index 07305a93fa..46f4fc3330 100644
--- a/src/google/protobuf/compiler/csharp/csharp_helpers.cc
+++ b/src/google/protobuf/compiler/csharp/csharp_helpers.cc
@@ -251,7 +251,13 @@ std::string GetFieldConstantName(const FieldDescriptor* field) {
 std::string GetPropertyName(const FieldDescriptor* descriptor) {
   // TODO(jtattermusch): consider introducing csharp_property_name field option
   std::string property_name = UnderscoresToPascalCase(GetFieldName(descriptor));
-  if (property_name == descriptor->containing_type()->name()) {
+  // Avoid either our own type name or reserved names. Note that not all names
+  // are reserved - a field called to_string, write_to etc would still cause a problem.
+  // There are various ways of ending up with naming collisions, but we try to avoid obvious
+  // ones.
+  if (property_name == descriptor->containing_type()->name()
+      || property_name == "Types"
+      || property_name == "Descriptor") {
     property_name += "_";
   }
   return property_name;