diff --git a/MDAF/MDAF.py b/MDAF/MDAF.py
index 95b763e..62e1eba 100644
--- a/MDAF/MDAF.py
+++ b/MDAF/MDAF.py
@@ -95,11 +95,8 @@ def measure(heuristicpath, funcpath, args, connection):
     upper = funcChars['upper']
     lower = funcChars['lower']
 
-    if upper is not list: 
-        print(type(upper))
-        print(upper is not list)
-        upper = [upper for i in range(n)]
-    if lower is not list: lower = [lower for i in range(n)]
+    if isinstance(upper, list): upper = [upper for i in range(n)]
+    if isinstance(lower, list): lower = [lower for i in range(n)]
 
     scale = list()
     for i in range(n):