diff --git a/test/firtool/combinational-loops.fir b/test/firtool/combinational-loops.fir
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+++ b/test/firtool/combinational-loops.fir
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+; RUN: firtool %s -split-input-file -verify-diagnostics
+
+; Check that we resolve last connect semantics before detecting combinational
+; loops.
+FIRRTL version 4.0.0
+circuit CombinationalLoop:
+  public module CombinationalLoop:
+    output o : UInt<1>
+    wire w : UInt<1>
+    connect w, w
+    connect w, UInt<1>(0)
+    connect o, w