diff --git a/python/src/com/jetbrains/python/psi/impl/PyCallExpressionHelper.java b/python/src/com/jetbrains/python/psi/impl/PyCallExpressionHelper.java
index bd33be42b4af..19fa72a1a97b 100644
--- a/python/src/com/jetbrains/python/psi/impl/PyCallExpressionHelper.java
+++ b/python/src/com/jetbrains/python/psi/impl/PyCallExpressionHelper.java
@@ -507,7 +507,9 @@ public class PyCallExpressionHelper {
                 }
               }
             }
-            else if (((PyFile)call.getContainingFile()).getLanguageLevel().isPy3K() && containingClass != null) {
+            else if ((call.getContainingFile() instanceof PyFile) &&
+                     ((PyFile)call.getContainingFile()).getLanguageLevel().isPy3K() &&
+                     (containingClass != null)) {
               return new Maybe<PyType>(getSuperClassUnionType(containingClass));
             }
           }