diff --git a/src/compiler/simplified-lowering.cc b/src/compiler/simplified-lowering.cc
index 75de8ecc42..be599beaca 100644
--- a/src/compiler/simplified-lowering.cc
+++ b/src/compiler/simplified-lowering.cc
@@ -3943,10 +3943,15 @@ class RepresentationSelector {
         VisitUnop<T>(node, UseInfo::AnyTagged(), MachineRepresentation::kTagged,
                      inputType);
         if (lower<T>()) {
-          CHECK_IMPLIES(!FLAG_fuzzing, inputType.CanBeAsserted());
           if (inputType.CanBeAsserted()) {
             ChangeOp(node, simplified()->AssertType(inputType));
           } else {
+            if (!FLAG_fuzzing) {
+#ifdef DEBUG
+              inputType.Print();
+#endif
+              FATAL("%%VerifyType: unsupported type");
+            }
             DeferReplacement(node, node->InputAt(0));
           }
         }
diff --git a/test/mjsunit/compiler/verify-type.js b/test/mjsunit/compiler/verify-type.js
new file mode 100644
index 0000000000..96df39b2ab
--- /dev/null
+++ b/test/mjsunit/compiler/verify-type.js
@@ -0,0 +1,14 @@
+// Copyright 2021 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Flags: --allow-natives-syntax  --no-stress-opt
+
+function foo(x) {
+  return %VerifyType(x * x);
+}
+
+%PrepareFunctionForOptimization(foo);
+foo(42);
+%OptimizeFunctionOnNextCall(foo);
+foo(42);