export CPPFLAGS so it can be used like CFLAGS/normal
diff --git a/Makefile b/Makefile
index 4489f4a..de0e5c8 100644
--- a/Makefile
+++ b/Makefile
@@ -40,7 +40,7 @@
 HAS_NUMA=$(shell sh tools/scripts/numa_test.sh)
 
 export CFLAGS += -Wall $(CROSS_CFLAGS)
-export CC AR RANLIB LDFLAGS HAS_NUMA
+export CC AR RANLIB CPPFLAGS LDFLAGS HAS_NUMA
 
 -include config.mk