diff --git a/configure.ac b/configure.ac
index 0b38b93..bcc95e6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -7,6 +7,8 @@ AM_SILENT_RULES([yes])
 
 AC_CONFIG_MACRO_DIRS([m4])
 
+CFLAGS="$CFLAGS -std=gnu11"
+
 dnl include release helper
 RELMAKE='-include osmo-release.mk'
 AC_SUBST([RELMAKE])