diff --git a/Makefile b/Makefile
index c7f74da..0eef015 100644
--- a/Makefile
+++ b/Makefile
@@ -22,7 +22,7 @@ SUBDIR_LIB := libslunkcrypt
 # Flags
 # ---------------------------------------------------------------------------
 
-CFLAGS = -I$(SUBDIR_LIB)/include -std=c99 -Wall -march=$(MARCH) -mtune=$(MTUNE)
+CFLAGS = -I$(SUBDIR_LIB)/include -std=gnu99 -Wall -march=$(MARCH) -mtune=$(MTUNE)
 LDFLGS =
 
 ifeq ($(DEBUG),1)