diff --git a/test/common.js b/test/common.js
index 8a5a5f14c1cba0..17d951876e59d7 100644
--- a/test/common.js
+++ b/test/common.js
@@ -402,8 +402,10 @@ function runCallChecks(exitCode) {
 }
 
 
-exports.mustCall = function(fn, expected) {
-  if (typeof expected !== 'number') expected = 1;
+exports.mustCall = function(fn, expected = 1) {
+  if (typeof expected !== 'number' || expected < 0) {
+    throw new RangeError(`Invalid expected value: ${expected}`);
+  }
 
   var context = {
     expected: expected,
diff --git a/test/parallel/test-common.js b/test/parallel/test-common.js
index 5ffe2c351503c1..0cc4313c74f27d 100644
--- a/test/parallel/test-common.js
+++ b/test/parallel/test-common.js
@@ -5,3 +5,12 @@ var assert = require('assert');
 common.globalCheck = false;
 global.gc = 42;  // Not a valid global unless --expose_gc is set.
 assert.deepStrictEqual(common.leakedGlobals(), ['gc']);
+
+
+assert.throws(function() {
+  common.mustCall(function() {}, 'foo')();
+}, /invalid expected value: foo/i);
+
+assert.throws(function() {
+  common.mustCall(function() {}, /foo/)();
+}, /invalid expected value: \/foo\//i);