diff --git a/src/finn/custom_op/fpgadataflow/tlastmarker.py b/src/finn/custom_op/fpgadataflow/tlastmarker.py
index 091c447f4e4e650586730d32db55572bdf69ed5c..d1bbca7a8d1c2db91e047fed505faa19024fbf0e 100644
--- a/src/finn/custom_op/fpgadataflow/tlastmarker.py
+++ b/src/finn/custom_op/fpgadataflow/tlastmarker.py
@@ -58,6 +58,7 @@ class TLastMarker(HLSCustomOp):
             "#pragma HLS PIPELINE II=1",
             "OutDType t;",
             "t.set_data(in0.read());",
+            "t.set_keep(-1);",
             "t.set_last(i==(NumIters-1));",
             "out.write(t);",
             "}",