diff --git a/pySDC/core/Sweeper.py b/pySDC/core/Sweeper.py
index fc53fa8fab..53e86cd161 100644
--- a/pySDC/core/Sweeper.py
+++ b/pySDC/core/Sweeper.py
@@ -20,7 +20,7 @@ def __init__(self, pars):
         self.initial_guess = 'spread'
 
         for k, v in pars.items():
-            if k is not 'collocation_class':
+            if k != 'collocation_class':
                 setattr(self, k, v)
 
         self._freeze()