diff --git a/number_test.go b/number_test.go
index 8db01cf..070cf15 100644
--- a/number_test.go
+++ b/number_test.go
@@ -34,11 +34,11 @@ func TestNumber_toString(t *testing.T) {
 
 		test(`raise:
             new Number(451).toString(1);
-        `, "RangeError: RangeError: toString() radix must be between 2 and 36")
+        `, "RangeError: toString() radix must be between 2 and 36")
 
 		test(`raise:
             new Number(451).toString(Infinity);
-        `, "RangeError: RangeError: toString() radix must be between 2 and 36")
+        `, "RangeError: toString() radix must be between 2 and 36")
 
 		test(`
             new Number(NaN).toString()