diff --git a/config/rules.mk b/config/rules.mk
index 8ffb0426784..eb6857208cb 100644
--- a/config/rules.mk
+++ b/config/rules.mk
@@ -1869,7 +1869,7 @@ FORCE:
 # so the files must be built serially
 # This requires a recent version of gmake 
 ifeq ($(OS_ARCH),WINNT)
-ifneq (,$(MOZ_DEBUG)$(MOZ_PROFILE))
+ifneq (,$(MOZ_DEBUG)$(MOZ_PROFILE)$(MOZ_COVERAGE))
 .NOTPARALLEL::
 endif
 endif