diff --git a/js/src/tests/lib/jittests.py b/js/src/tests/lib/jittests.py
index ce7585b85267..7ba9bdba60df 100755
--- a/js/src/tests/lib/jittests.py
+++ b/js/src/tests/lib/jittests.py
@@ -545,8 +545,7 @@ def check_output(out, err, rc, timed_out, test, options):
 
         # Allow a non-zero exit code if we want to allow unhandlable OOM, but
         # only if we actually got unhandlable OOM.
-        if test.allow_unhandlable_oom \
-           and 'Assertion failure: [unhandlable oom]' in err:
+        if test.allow_unhandlable_oom and 'MOZ_CRASH([unhandlable oom]' in err:
             return True
 
         # Allow a non-zero exit code if we want to all too-much-recursion and
diff --git a/js/src/vm/JSContext.cpp b/js/src/vm/JSContext.cpp
index eee75f0bdc74..56ed64c053b1 100644
--- a/js/src/vm/JSContext.cpp
+++ b/js/src/vm/JSContext.cpp
@@ -1516,8 +1516,13 @@ void AutoEnterOOMUnsafeRegion::crash(const char* reason) {
   char msgbuf[1024];
   js::NoteIntentionalCrash();
   SprintfLiteral(msgbuf, "[unhandlable oom] %s", reason);
-  MOZ_ReportAssertionFailure(msgbuf, __FILE__, __LINE__);
-  MOZ_CRASH();
+#ifndef DEBUG
+  // In non-DEBUG builds MOZ_CRASH normally doesn't print to stderr so we have
+  // to do this explicitly (the jit-test allow-unhandlable-oom annotation and
+  // fuzzers depend on it).
+  MOZ_ReportCrash(msgbuf, __FILE__, __LINE__);
+#endif
+  MOZ_CRASH_UNSAFE(msgbuf);
 }
 
 AutoEnterOOMUnsafeRegion::AnnotateOOMAllocationSizeCallback