+diff --git a/Makefile b/Makefile
+index 8111c9b..8d8fe87 100644
+--- a/Makefile
++++ b/Makefile
+@@ -2,7 +2,7 @@
+ # DESTDIR is completely respected
+ CC := gcc
+ AR := ar
+-CFLAGS := -Wall $(CFLAGS)
++CFLAGS := -Wall $(CFLAGS) $(CPPFLAGS)
+ XLDFLAGS := $(LDFLAGS)
+ LDFLAGS := -L. -lossp $(LDFLAGS)
+ prefix := /usr/local