--- fio-2.1/Makefile	2013-05-14 23:42:26.000000000 -0700
+++ fio-2.1/patched/Makefile	2013-07-14 18:21:18.987246429 -0700
@@ -15,7 +15,7 @@
 DEBUGFLAGS = -D_FORTIFY_SOURCE=2 -DFIO_INC_DEBUG
 CPPFLAGS= -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 $(DEBUGFLAGS)
 OPTFLAGS= -O3 -g -ffast-math
-CFLAGS	= -std=gnu99 -Wwrite-strings -Wall -Wdeclaration-after-statement $(OPTFLAGS) $(EXTFLAGS) $(BUILD_CFLAGS)
+CFLAGS	+= -std=gnu99 -Wwrite-strings -Wall -Wdeclaration-after-statement $(OPTFLAGS) $(EXTFLAGS) $(BUILD_CFLAGS)
 LIBS	+= -lm $(EXTLIBS)
 PROGS	= fio
 SCRIPTS = fio_generate_plots