diff --git a/maraboupy/MarabouNetworkONNX.py b/maraboupy/MarabouNetworkONNX.py
index 1c2eecf1e..4b6e2b983 100644
--- a/maraboupy/MarabouNetworkONNX.py
+++ b/maraboupy/MarabouNetworkONNX.py
@@ -342,7 +342,7 @@ def transpose(self, node):
         if inputName in self.varMap:
             self.varMap[nodeName] = np.transpose(self.varMap[node.input[0]], perm)
         elif inputName in self.constantMap:
-            self.constantMap[nodeName] = np.transpose(self.constant[inputName], perm)
+            self.constantMap[nodeName] = np.transpose(self.constantMap[inputName], perm)
     
     def maxpoolEquations(self, node, makeEquations):
         """
@@ -812,4 +812,4 @@ def evaluateWithoutMarabou(self, inputValues):
                 printf("Not sure how to cast input to graph input of type %s" % onnxType)
                 raise NotImplementedError
             input_dict[inputName] = inputValues[i].reshape(self.inputVars[i].shape).astype(inputType)
-        return sess.run([self.outputName],input_dict)[0]
\ No newline at end of file
+        return sess.run([self.outputName],input_dict)[0]