diff --git a/s/build b/s/build
index 40ab81283..d36cbbf13 100755
--- a/s/build
+++ b/s/build
@@ -29,6 +29,7 @@ if [ ! -d $ROOT/$BIN_DIR ]; then
   exit
 fi
 
+git submodule update
 cd $ROOT/$BIN_DIR
 make $MAKEOPTS && make test
 cd $OLDPWD