diff --git a/tools/netlist/tests/NameTests.cpp b/tools/netlist/tests/NameTests.cpp
index ba966bddc..fbbf015bc 100644
--- a/tools/netlist/tests/NameTests.cpp
+++ b/tools/netlist/tests/NameTests.cpp
@@ -78,7 +78,7 @@ module t33 #(
 
   property test_prop;
     @(posedge clk) disable iff (MODE != 3'd0)
-    !($isunknown({a,b,c})) &
+    (!$isunknown({a,b,c})) &
       a & (b == 2'b01)
       |-> (c_n[15:12] == c[15:12]);
   endproperty