diff --git a/Makefile b/Makefile
index f78db9151..a6e8959d0 100644
--- a/Makefile
+++ b/Makefile
@@ -20,7 +20,7 @@
 
 all: oio.a test/run-tests test/run-benchmarks
 
-CFLAGS=-ansi -g
+CFLAGS=--std=gnu89 -g
 LINKFLAGS=-lm
 TESTS=test/echo-server.c test/test-*.c
 BENCHMARKS=test/echo-server.c test/benchmark-*.c