diff --git a/python/pydevSrc/com/jetbrains/python/debugger/PySignature.java b/python/pydevSrc/com/jetbrains/python/debugger/PySignature.java
index 9d13e6421554..521e6d17f155 100644
--- a/python/pydevSrc/com/jetbrains/python/debugger/PySignature.java
+++ b/python/pydevSrc/com/jetbrains/python/debugger/PySignature.java
@@ -120,7 +120,7 @@ public class PySignature {
         return myTypes.get(0);
       }
       else {
-        return StringUtil.join(myTypes, " or ");
+        return "Union[" + StringUtil.join(myTypes, ", ") + "]";
       }
     }