$FreeBSD$

--- Makefile.orig
+++ Makefile
@@ -61,7 +61,7 @@
 STRIP = -s
 endif
 INCLUDE = -Iinclude
-CFLAGS = $(OPT) $(WARN) $(INCLUDE) $(CFLAGS.EXTRA)
+CFLAGS += $(OPT) $(WARN) $(INCLUDE) $(CFLAGS.EXTRA)
 
 LIB.SRCS = src/glew.c
 LIB.OBJS = $(LIB.SRCS:.c=.o)