diff --git a/ipc/chromium/Makefile.in b/ipc/chromium/Makefile.in
index 6f09cfe76238..068ee99f56b0 100644
--- a/ipc/chromium/Makefile.in
+++ b/ipc/chromium/Makefile.in
@@ -330,6 +330,10 @@ endif # }
 endif # }
 endif # }
 
+ifdef MOZ_DEBUG
+OS_CFLAGS += -DUSE_DEBUG
+endif
+
 OS_CXXFLAGS += $(TK_CFLAGS)
 
 include $(topsrcdir)/config/rules.mk