diff --git a/lua/cmp/source.lua b/lua/cmp/source.lua
index 8a33e3d..d0d95e6 100644
--- a/lua/cmp/source.lua
+++ b/lua/cmp/source.lua
@@ -177,7 +177,7 @@ end
 ---Return the source is available or not.
 source.is_available = function(self)
   if self.source.is_available then
-    return self.source.is_available()
+    return self.source:is_available()
   end
   return true
 end