diff --git a/scripts.d/50-xvid.sh b/scripts.d/50-xvid.sh
index a4a77e2..01fc6f7 100755
--- a/scripts.d/50-xvid.sh
+++ b/scripts.d/50-xvid.sh
@@ -36,6 +36,8 @@ ffbuild_dockerbuild() {
         return -1
     fi
 
+    export CFLAGS="$CFLAGS -std=gnu99"
+
     ./configure "${myconf[@]}"
     make -j$(nproc)
     make install