diff --git a/src/finn/custom_op/fpgadataflow/concat.py b/src/finn/custom_op/fpgadataflow/concat.py
index 431c06af14d6cc112070a4425b1a2d823a2e8f48..c591cdec6c8343d2fc112fb53b8f095f25134175 100644
--- a/src/finn/custom_op/fpgadataflow/concat.py
+++ b/src/finn/custom_op/fpgadataflow/concat.py
@@ -102,7 +102,8 @@ class StreamingConcat(HLSCustomOp):
     def verify_node(self):
         pass
 
-    def get_input_datatype(self):
+    def get_input_datatype(self, ind=0):
+        # input dt identical for all inputs
         return DataType[self.get_nodeattr("inputDataType")]
 
     def get_output_datatype(self):