Fix custom options behaviour
diff --git a/src/ProtocolBuffers.Test/GeneratedMessageTest.cs b/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
index 1980bbc..69c5ac3 100644
--- a/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
+++ b/src/ProtocolBuffers.Test/GeneratedMessageTest.cs
@@ -97,7 +97,7 @@
       try {
         builder.Build();
         Assert.Fail("Should have thrown exception.");
-      } catch (InvalidOperationException e) {
+      } catch (InvalidOperationException) {
         // Success.
       }
     }