--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -317,16 +317,17 @@ def call(*args, **kwargs):
 
 def killPid(pid, log):
     # see also https://bugzilla.mozilla.org/show_bug.cgi?id=911249#c58
     try:
         os.kill(pid, getattr(signal, "SIGKILL", signal.SIGTERM))
     except Exception as e:
         log.info("Failed to kill process %d: %s" % (pid, str(e)))
 
+
 if mozinfo.isWin:
     import ctypes.wintypes
 
     def isPidAlive(pid):
         STILL_ACTIVE = 259
         PROCESS_QUERY_LIMITED_INFORMATION = 0x1000
         pHandle = ctypes.windll.kernel32.OpenProcess(
             PROCESS_QUERY_LIMITED_INFORMATION,
@@ -2353,16 +2354,17 @@ toolbar#nav-bar {
 
         if self.browserEnv is None:
             return 1
 
         if self.mozLogs:
             self.browserEnv["MOZ_LOG_FILE"] = "{}/moz-pid=%PID-uid={}.log".format(
                 self.browserEnv["MOZ_UPLOAD_DIR"], str(uuid.uuid4()))
 
+        status = 0
         try:
             self.startServers(options, debuggerInfo)
 
             if options.immersiveMode:
                 options.browserArgs.extend(('-firefoxpath', options.app))
                 options.app = self.immersiveHelperPath
 
             if options.jsdebugger:
@@ -2412,33 +2414,35 @@ toolbar#nav-bar {
                 testURL = self.buildTestURL(options, scheme=scheme)
 
                 self.buildURLOptions(options, self.browserEnv)
                 if self.urlOpts:
                     testURL += "?" + "&".join(self.urlOpts)
 
                 self.log.info("runtests.py | Running with e10s: {}".format(options.e10s))
                 self.log.info("runtests.py | Running tests: start.\n")
-                status = self.runApp(testURL,
-                                     self.browserEnv,
-                                     options.app,
-                                     profile=self.profile,
-                                     extraArgs=options.browserArgs,
-                                     utilityPath=options.utilityPath,
-                                     debuggerInfo=debuggerInfo,
-                                     valgrindPath=valgrindPath,
-                                     valgrindArgs=valgrindArgs,
-                                     valgrindSuppFiles=valgrindSuppFiles,
-                                     symbolsPath=options.symbolsPath,
-                                     timeout=timeout,
-                                     detectShutdownLeaks=detectShutdownLeaks,
-                                     screenshotOnFail=options.screenshotOnFail,
-                                     bisectChunk=options.bisectChunk,
-                                     marionette_args=marionette_args,
-                                     )
+                ret = self.runApp(
+                    testURL,
+                    self.browserEnv,
+                    options.app,
+                    profile=self.profile,
+                    extraArgs=options.browserArgs,
+                    utilityPath=options.utilityPath,
+                    debuggerInfo=debuggerInfo,
+                    valgrindPath=valgrindPath,
+                    valgrindArgs=valgrindArgs,
+                    valgrindSuppFiles=valgrindSuppFiles,
+                    symbolsPath=options.symbolsPath,
+                    timeout=timeout,
+                    detectShutdownLeaks=detectShutdownLeaks,
+                    screenshotOnFail=options.screenshotOnFail,
+                    bisectChunk=options.bisectChunk,
+                    marionette_args=marionette_args,
+                )
+                status = ret or status
         except KeyboardInterrupt:
             self.log.info("runtests.py | Received keyboard interrupt.\n")
             status = -1
         except:
             traceback.print_exc()
             self.log.error(
                 "Automation Error: Received unexpected exception while running application\n")
             status = 1
@@ -2730,10 +2734,11 @@ def cli(args=sys.argv[1:]):
     parser = MochitestArgumentParser(app='generic')
     options = parser.parse_args(args)
     if options is None:
         # parsing error
         sys.exit(1)
 
     return run_test_harness(parser, options)
 
+
 if __name__ == "__main__":
     sys.exit(cli())