--- multipath-tools-0.8.5-eecfcba/Makefile.inc
+++ multipath-tools-0.8.5-eecfcba/Makefile.inc
@@ -98,7 +98,8 @@
 		  -Werror=implicit-function-declaration -Werror=format-security \
 		  $(WNOCLOBBERED) -Werror=cast-qual $(ERROR_DISCARDED_QUALIFIERS)
 CPPFLAGS	:= -Wp,-D_FORTIFY_SOURCE=2 
-CFLAGS		:= --std=gnu99 $(CFLAGS) $(OPTFLAGS) $(WARNFLAGS) -pipe \
+CFLAGS		?= $(OPTFLAGS) $(WARNFLAGS) -pipe
+CFLAGS		+= --std=gnu99 \
 		   -DBIN_DIR=\"$(bindir)\" -DLIB_STRING=\"${LIB}\" -DRUN_DIR=\"${RUN}\" \
 		   -MMD -MP
 BIN_CFLAGS	= -fPIE -DPIE