diff --git a/lua_examples/lfs/lfs_fragments.lua b/lua_examples/lfs/lfs_fragments.lua
index 83f70f2a..8863b230 100644
--- a/lua_examples/lfs/lfs_fragments.lua
+++ b/lua_examples/lfs/lfs_fragments.lua
@@ -7,7 +7,7 @@
 do
   local _,ma,fa=node.flashindex()
   for n,v in pairs{LFS_MAPPED=ma, LFS_BASE=fa, SPIFFS_BASE=sa} do
-    print(('export %s=""0x%x"'):format(n, v)
+    print(('export %s=""0x%x"'):format(n, v))
   end
 end
 --
diff --git a/lua_examples/mqtt/mqtt_file.lua b/lua_examples/mqtt/mqtt_file.lua
index 6d0d88e4..4d192325 100644
--- a/lua_examples/mqtt/mqtt_file.lua
+++ b/lua_examples/mqtt/mqtt_file.lua
@@ -43,7 +43,7 @@ m:on("offline", function(conn)
 end)
 m:on("message",dispatch )
 -- Lua: mqtt:connect( host, port, secure, auto_reconnect, function(client) )
-m:connect(192.168.18.88,1883,0,1)
+m:connect("192.168.18.88",1883,0,1)
 
 -- usage:
 -- another client(pc) subscribe to /topic2, will receive the test.lua content.
diff --git a/tools/pr-build.sh b/tools/pr-build.sh
index f7866f71..0670c741 100644
--- a/tools/pr-build.sh
+++ b/tools/pr-build.sh
@@ -29,4 +29,8 @@ cd "$TRAVIS_BUILD_DIR"/ld || exit
 cd "$TRAVIS_BUILD_DIR" || exit
 make clean
 make
+
+LUA_FILES=`find lua_modules lua_examples -iname "*.lua"`
+echo checking $LUA_FILES
+./luac.cross -p $LUA_FILES
 )