diff --git a/googlemock/include/gmock/gmock-spec-builders.h b/googlemock/include/gmock/gmock-spec-builders.h
index 81ee345..735a3bc 100644
--- a/googlemock/include/gmock/gmock-spec-builders.h
+++ b/googlemock/include/gmock/gmock-spec-builders.h
@@ -1870,7 +1870,7 @@
   }
 
  private:
-  mutable internal::FunctionMocker<R(Args...)> mock_;
+  internal::FunctionMocker<R(Args...)> mock_;
 };
 
 // The style guide prohibits "using" statements in a namespace scope