diff --git a/Makefile.rules b/Makefile.rules
index 55d4d1b7038..74b5a32ae85 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -226,7 +226,7 @@ else
 
     # Darwin requires -fstrict-aliasing to be explicitly enabled.
     ifeq ($(OS),Darwin)
-      EXTRA_OPTIONS += -fstrict-aliasing
+      EXTRA_OPTIONS += -fstrict-aliasing -Wstrict-aliasing
     endif
 
     CXX.Flags += $(OPTIMIZE_OPTION) $(OmitFramePointer)