diff --git a/src/finn/custom_op/fpgadataflow/__init__.py b/src/finn/custom_op/fpgadataflow/__init__.py
index c4ee7944cf8ceea48bc419c48b8f0d5dbd7cd70f..4231be7c523a5a510de89fb1202dc7bbcf30d39f 100644
--- a/src/finn/custom_op/fpgadataflow/__init__.py
+++ b/src/finn/custom_op/fpgadataflow/__init__.py
@@ -75,6 +75,7 @@ class HLSCustomOp(CustomOp):
             "rtlsim_trace": ("s", False, ""),
             "res_estimate": ("s", False, ""),
             "res_hls": ("s", False, ""),
+            "res_synth": ("s", False, ""),
         }
 
     def node_res_estimation(self):