diff --git a/js/src/jsapi-tests/testMutedErrors.cpp b/js/src/jsapi-tests/testMutedErrors.cpp
index f691ba115c10..44bc6154b11b 100644
--- a/js/src/jsapi-tests/testMutedErrors.cpp
+++ b/js/src/jsapi-tests/testMutedErrors.cpp
@@ -5,6 +5,8 @@
 #include "jsfriendapi.h"
 #include "jsapi-tests/tests.h"
 
+using mozilla::UniquePtr;
+
 static bool sErrorReportMuted = false;
 BEGIN_TEST(testMutedErrors)
 {
@@ -45,7 +47,7 @@ bool
 eval(const char* asciiChars, bool mutedErrors, JS::MutableHandleValue rval)
 {
     size_t len = strlen(asciiChars);
-    char16_t* chars = new char16_t[len+1];
+    UniquePtr<char16_t[]> chars(new char16_t[len+1]);
     for (size_t i = 0; i < len; ++i)
         chars[i] = asciiChars[i];
     chars[len] = 0;
@@ -60,10 +62,7 @@ eval(const char* asciiChars, bool mutedErrors, JS::MutableHandleValue rval)
     options.setMutedErrors(mutedErrors)
            .setFileAndLine("", 0);
 
-    bool ok = JS::Evaluate(cx, options, chars, len, rval);
-
-    delete[] chars;
-    return ok;
+    return JS::Evaluate(cx, options, chars.get(), len, rval);
 }
 
 bool