diff --git a/vars/build.vars b/vars/build.vars
index cd73983..c100e5b 100644
--- a/vars/build.vars
+++ b/vars/build.vars
@@ -983,6 +983,7 @@ LEAF_PACKAGES_PREFIX="${PREFIX_NATIVE}";
 : ${PKG_SMALLBASIC_URLS_GIT:="SmallBASIC=https://github.com/smallbasic/SmallBASIC@master"};
 : ${PKG_SMALLBASIC_BUILD_DIR:=${PKG_SMALLBASIC_SUBDIR}};
 : ${PKG_SMALLBASIC_CONFIGURE_ARGS_EXTRA:=--program-prefix=};
+: ${PKG_SMALLBASIC_CFLAGS_CONFIGURE_EXTRA:=-std=gnu99};
 : ${PKG_SOCAT_SHA256SUM:=ce3efc17e3e544876ebce7cd6c85b3c279fda057b2857fcaaf67b9ab8bdaf034};
 : ${PKG_SOCAT_VERSION:=1.7.3.2};
 : ${PKG_SOCAT_URL:=http://www.dest-unreach.org/socat/download/socat-1.7.3.2.tar.gz};