diff --git a/tools/flex/Makefile b/tools/flex/Makefile
index 659324a647e..8d23448422f 100644
--- a/tools/flex/Makefile
+++ b/tools/flex/Makefile
@@ -14,6 +14,8 @@ PKG_SOURCE_URL:=@SF/$(PKG_NAME)
 PKG_MD5SUM:=10714e50cea54dc7a227e3eddcd44d57
 PKG_CAT:=bzcat
 
+HOST_BUILD_PARALLEL:=1
+
 include $(INCLUDE_DIR)/host-build.mk
 
 HOST_LDFLAGS += $(HOST_STATIC_LINKING)