diff --git a/packages/compiler/src/frontend/lowering/lower-assert.ts b/packages/compiler/src/frontend/lowering/lower-assert.ts
index bc51a9382..b996abed7 100644
--- a/packages/compiler/src/frontend/lowering/lower-assert.ts
+++ b/packages/compiler/src/frontend/lowering/lower-assert.ts
@@ -1355,7 +1355,7 @@ function lowerAssertMatch(
     lowerer.noLowering(`${surface} with ${expr.arguments.nodes.length} arguments`, expr);
   }
   const s = lowerer.lowerExprExpecting(expr.arguments.nodes[0]!, STRING);
-  const re = lowerer.lowerExpr(expr.arguments.nodes[1]!);
+  const re = lowerExpectedValue(lowerer, expr.arguments.nodes[1]!);
   if (re.type.kind !== "regex") {
     lowerer.noLowering(
       `${surface} with a non-regex pattern`,
@@ -1420,6 +1420,18 @@ function inErrorHierarchy(lowerer: Lowerer, className: string): boolean {
   return false;
 }
 
+/** An expected string or regex: a value JavaScript stores checked-dynamic
+ * (an object literal's field, an untyped binding) converts to the string
+ * or regex its checker type names, so the comparison takes that arm. */
+function lowerExpectedValue(lowerer: Lowerer, node: ts.Expression): IrExpr {
+  const value = lowerer.lowerExpr(node);
+  if (value.type.kind !== "dyn") return value;
+  const expected = lowerer.mapTypeOf(lowerer.typeOf(node));
+  return expected?.kind === "string" || expected?.kind === "regex"
+    ? lowerer.coerceToExpected(value, expected)
+    : value;
+}
+
 /** Classify the expected argument: string → message, regex value → the
  * regex test over String(error), an error-class identifier → instanceof,
  * an object LITERAL over name/message/code (string or regex values) →
@@ -1436,7 +1448,7 @@ function classifyThrowsExpected(
     return { form: "message", msg: m.msg, hasMsg: m.hasMsg };
   }
   if (expectedT?.kind === "regex") {
-    return { form: "regex", value: lowerer.lowerExpr(node) };
+    return { form: "regex", value: lowerExpectedValue(lowerer, node) };
   }
   const sym = ts.isIdentifier(node) ? lowerer.resolveValueSymbol(node) : null;
   const info =
@@ -1509,7 +1521,7 @@ function classifyThrowsExpected(
         );
       }
       const valueNode = ts.isPropertyAssignment(named) ? named.initializer : named.name;
-      const value = lowerer.lowerExpr(valueNode);
+      const value = lowerExpectedValue(lowerer, valueNode);
       if (value.type.kind === "string") {
         byId.set(id, { id, kind: "str", value, enameBake: null });
       } else if (value.type.kind === "regex") {
diff --git a/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/8160-assert-expected-from-fields.cjs.json b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/8160-assert-expected-from-fields.cjs.json
new file mode 100644
index 000000000..fcaacbbee
--- /dev/null
+++ b/packages/compiler/test/ts7/baselines/order-parity/tests/corpus/8160-assert-expected-from-fields.cjs.json
@@ -0,0 +1,6 @@
+{
+ "order": [
+  "<repo>/tests/corpus/8160-assert-expected-from-fields.cjs"
+ ],
+ "diags": []
+}
diff --git a/tests/corpus/8160-assert-expected-from-fields.cjs b/tests/corpus/8160-assert-expected-from-fields.cjs
new file mode 100644
index 000000000..4c16bd78f
--- /dev/null
+++ b/tests/corpus/8160-assert-expected-from-fields.cjs
@@ -0,0 +1,58 @@
+// Expected errors stored in an object literal's fields: a JavaScript
+// object keeps its fields checked-dynamic, and assert.throws, assert.match
+// and the expected-object form convert them to the regex or string the
+// fields hold.
+"use strict";
+const assert = require("assert");
+
+const errMessages = {
+  auth: / auth/,
+  state: / state/,
+  length: /Invalid initialization vector/,
+  code: "ERR_CRYPTO_INVALID_IV",
+};
+
+const error = (message, code) => {
+  const e = new Error(message);
+  if (code) e.code = code;
+  return e;
+};
+
+assert.throws(() => {
+  throw error("Unsupported state or unable to authenticate data");
+}, errMessages.auth);
+assert.throws(() => {
+  throw error("Invalid state for operation getAuthTag");
+}, errMessages.state);
+assert.throws(
+  () => {
+    throw error("Invalid initialization vector", "ERR_CRYPTO_INVALID_IV");
+  },
+  { code: errMessages.code, message: errMessages.length },
+);
+assert.match("unable to auth", errMessages.auth);
+assert.doesNotMatch("no match here", errMessages.state);
+
+const report = (label, run) => {
+  try {
+    run();
+    console.log(label, "passed");
+  } catch (error) {
+    console.log(label, error.name, error.code, error.message.split("\n")[0]);
+  }
+};
+report("wrong message", () =>
+  assert.throws(() => {
+    throw error("something else");
+  }, errMessages.length),
+);
+report("wrong code", () =>
+  assert.throws(
+    () => {
+      throw error("Invalid initialization vector", "ERR_OTHER");
+    },
+    { code: errMessages.code },
+  ),
+);
+report("match", () => assert.match("plain text", errMessages.auth));
+console.log("done");
diff --git a/tests/harness/corpus-costs/8160-assert-expected-from-fields.cjs.json b/tests/harness/corpus-costs/8160-assert-expected-from-fields.cjs.json
new file mode 100644
index 000000000..cdfeabea9
--- /dev/null
+++ b/tests/harness/corpus-costs/8160-assert-expected-from-fields.cjs.json
@@ -0,0 +1 @@
+{ "plain": 2656, "san": 5234 }