diff --git a/techlibs/xilinx/synth_xilinx.cc b/techlibs/xilinx/synth_xilinx.cc
index 5ba8c0e10..3c5599e4e 100644
--- a/techlibs/xilinx/synth_xilinx.cc
+++ b/techlibs/xilinx/synth_xilinx.cc
@@ -318,7 +318,7 @@ struct SynthXilinxPass : public ScriptPass
 				run("flatten", "(with '-flatten')");
 			active_design->scratchpad_unset("tribuf.added_something");
 			run("tribuf -logic");
-			if (!do_iopad && active_design->scratchpad_get_bool("tribuf.added_something"))
+			if (noiopad && active_design->scratchpad_get_bool("tribuf.added_something"))
 				log_error("Tristate buffers are unsupported without the '-iopad' option.\n");
 			run("deminout");
 			run("opt_expr");