diff --git a/python/mozbuild/mozbuild/backend/base.py b/python/mozbuild/mozbuild/backend/base.py
index 3a875ed90ed..6a4f6b3eba5 100644
--- a/python/mozbuild/mozbuild/backend/base.py
+++ b/python/mozbuild/mozbuild/backend/base.py
@@ -153,7 +153,8 @@ class BuildBackend(LoggingMixin):
                 not os.path.exists(self._backend_output_list_file):
             with open(self._backend_output_list_file, 'w') as fh:
                 fh.write('\n'.join(sorted(self._backend_output_files)))
-        elif self._updated_count:
+        else:
+            # Always update its mtime.
             with open(self._backend_output_list_file, 'a'):
                 os.utime(self._backend_output_list_file, None)
 
diff --git a/python/mozbuild/mozbuild/backend/recursivemake.py b/python/mozbuild/mozbuild/backend/recursivemake.py
index db1755365af..33767778b34 100644
--- a/python/mozbuild/mozbuild/backend/recursivemake.py
+++ b/python/mozbuild/mozbuild/backend/recursivemake.py
@@ -850,10 +850,6 @@ class RecursiveMakeBackend(CommonBackend):
             for path in inputs:
                 backend_deps.write('%s:\n' % path)
 
-        with open(self._backend_output_list_file, 'a'):
-            pass
-        os.utime(self._backend_output_list_file, None)
-
         # Make the master test manifest files.
         for flavor, t in self._test_manifests.items():
             install_prefix, manifests = t