--- a/GNUmakefile
+++ b/GNUmakefile
@@ -64,7 +64,7 @@
 acc: acc.c
 	$(CC) -o $@ $< $(CFLAGS) $(LDFLAGS) -lowfat
 
-CC:=$(DIET) $(CC)
+override CC:=$(DIET) $(CC)
 
 pthreadbench: pthreadbench.o
 	$(CC) $< -o $@ -I. $(CFLAGS) $(LDFLAGS) $(LDLIBS) -lpthread