diff --git a/Source/JavaScriptCore/API/tests/testapi.cpp b/Source/JavaScriptCore/API/tests/testapi.cpp
index dc851c1..2a9f86a 100644
--- a/Source/JavaScriptCore/API/tests/testapi.cpp
+++ b/Source/JavaScriptCore/API/tests/testapi.cpp
@@ -524,7 +524,7 @@
 
 void TestAPI::promiseUnhandledRejection()
 {
-    JSObjectRef reject;
+    JSObjectRef reject = nullptr;
     JSValueRef exception = nullptr;
     static auto promise = JSObjectMakeDeferredPromise(context, nullptr, &reject, &exception);
     check(!exception, "creating a (reject-only) deferred promise should not throw");
diff --git a/Source/JavaScriptCore/ChangeLog b/Source/JavaScriptCore/ChangeLog
index 5ceafe0..3394a8d 100644
--- a/Source/JavaScriptCore/ChangeLog
+++ b/Source/JavaScriptCore/ChangeLog
@@ -1,3 +1,10 @@
+2019-12-06  Per Arne Vollan  <pvollan@apple.com>
+
+        Unreviewed build fix. Initialize local variable.
+
+        * API/tests/testapi.cpp:
+        (TestAPI::promiseUnhandledRejection):
+
 2019-12-06  Joonghun Park  <jh718.park@samsung.com>
 
         Unreviewed. Change the format string portable by using "%" PRIx64