diff --git a/src/tests/userdata.rs b/src/tests/userdata.rs
index 4af0f6e..4a51000 100644
--- a/src/tests/userdata.rs
+++ b/src/tests/userdata.rs
@@ -1,4 +1,3 @@
-
 use std::sync::Arc;
 
 use {ExternalError, Function, Lua, MetaMethod, String, UserData, UserDataMethods};
@@ -179,4 +178,5 @@ fn user_value() {
     let ud = lua.create_userdata(MyUserData).unwrap();
     ud.set_user_value("hello").unwrap();
     assert_eq!(ud.get_user_value::<String>().unwrap(), "hello");
+    assert!(ud.get_user_value::<u32>().is_err());
 }
diff --git a/src/userdata.rs b/src/userdata.rs
index c119911..e10f251 100644
--- a/src/userdata.rs
+++ b/src/userdata.rs
@@ -406,7 +406,7 @@ impl<'lua> AnyUserData<'lua> {
     pub fn set_user_value<V: ToLua<'lua>>(&self, v: V) -> Result<()> {
         let lua = self.0.lua;
         unsafe {
-            stack_guard(lua.state, 0, || {
+            stack_err_guard(lua.state, 0, || {
                 check_stack(lua.state, 2);
                 lua.push_ref(lua.state, &self.0);
                 lua.push_value(lua.state, v.to_lua(lua)?);
@@ -423,7 +423,7 @@ impl<'lua> AnyUserData<'lua> {
     pub fn get_user_value<V: FromLua<'lua>>(&self) -> Result<V> {
         let lua = self.0.lua;
         unsafe {
-            stack_guard(lua.state, 0, || {
+            stack_err_guard(lua.state, 0, || {
                 check_stack(lua.state, 2);
                 lua.push_ref(lua.state, &self.0);
                 ffi::lua_getuservalue(lua.state, -1);