--- a/toolkit/components/extensions/test/mochitest/test_chrome_ext_native_messaging.html
+++ b/toolkit/components/extensions/test/mochitest/test_chrome_ext_native_messaging.html
@@ -77,23 +77,32 @@ sys.stdout.write(struct.pack('@I', len(m
 sys.stdout.write(msg)
 sys.exit(0)
 `;
 
 const WONTDIE_BODY = String.raw`
 import signal
 import struct
 import sys
+import time
 
 signal.signal(signal.SIGTERM, signal.SIG_IGN)
 
+def spin():
+    while True:
+        try:
+            signal.pause()
+        except AttributeError:
+            time.sleep(5)
+
 while True:
     rawlen = sys.stdin.read(4)
     if len(rawlen) == 0:
-        signal.pause()
+        spin()
+
     msglen = struct.unpack('@I', rawlen)[0]
     msg = sys.stdin.read(msglen)
 
     sys.stdout.write(struct.pack('@I', msglen))
     sys.stdout.write(msg)
 `;
 
 const SCRIPTS = [