diff --git a/test/parallel/test-v8-flag-type-check.js b/test/parallel/test-v8-flag-type-check.js
index b5d4d7c2f12665..144e8f7a2e3d07 100644
--- a/test/parallel/test-v8-flag-type-check.js
+++ b/test/parallel/test-v8-flag-type-check.js
@@ -3,5 +3,7 @@ require('../common');
 const assert = require('assert');
 const v8 = require('v8');
 
-assert.throws(function() { v8.setFlagsFromString(1); }, TypeError);
-assert.throws(function() { v8.setFlagsFromString(); }, TypeError);
+assert.throws(function() { v8.setFlagsFromString(1); },
+              /^TypeError: v8 flag must be a string$/);
+assert.throws(function() { v8.setFlagsFromString(); },
+              /^TypeError: v8 flag is required$/);
diff --git a/test/parallel/test-v8-flags.js b/test/parallel/test-v8-flags.js
index 99384080516bb2..50d7047a5ddfa9 100644
--- a/test/parallel/test-v8-flags.js
+++ b/test/parallel/test-v8-flags.js
@@ -12,5 +12,7 @@ assert(eval('%_IsSmi(42)'));
 assert(vm.runInThisContext('%_IsSmi(43)'));
 
 v8.setFlagsFromString('--noallow_natives_syntax');
-assert.throws(function() { eval('%_IsSmi(44)'); }, SyntaxError);
-assert.throws(function() { vm.runInThisContext('%_IsSmi(45)'); }, SyntaxError);
+assert.throws(function() { eval('%_IsSmi(44)'); },
+              /^SyntaxError: Unexpected token %$/);
+assert.throws(function() { vm.runInThisContext('%_IsSmi(45)'); },
+              /^SyntaxError: Unexpected token %$/);