diff --git a/src/lua.rs b/src/lua.rs
index e4b44c1..9dcd438 100644
--- a/src/lua.rs
+++ b/src/lua.rs
@@ -1066,15 +1066,17 @@ impl<'lua, 'scope> Scope<'lua, 'scope> {
         R: ToLuaMulti<'callback>,
         F: 'scope + Fn(&'callback Lua, A) -> Result<R>,
     {
-        unsafe {
-            let f: Box<
-                Fn(&'callback Lua, MultiValue<'callback>) -> Result<MultiValue<'callback>> + 'scope,
-            > = Box::new(move |lua, args| {
-                func(lua, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua)
-            });
+        let f: Box<
+            Fn(&'callback Lua, MultiValue<'callback>) -> Result<MultiValue<'callback>> + 'scope,
+        > = Box::new(move |lua, args| func(lua, A::from_lua_multi(args, lua)?)?.to_lua_multi(lua));
 
+        unsafe {
             // SCARY, we are transmuting the 'scope lifetime to 'static.
-            let mut f = self.lua.create_callback_function(mem::transmute(f))?;
+            let f: Box<
+                Fn(&'callback Lua, MultiValue<'callback>) -> Result<MultiValue<'callback>>,
+            > = mem::transmute(f);
+
+            let mut f = self.lua.create_callback_function(f)?;
 
             f.0.drop_unref = false;
             let mut destructors = self.destructors.borrow_mut();