diff --git a/tools/continuous_build/clean_old_files.py b/tools/continuous_build/clean_old_files.py
index e87526edcf..94e210aa7a 100755
--- a/tools/continuous_build/clean_old_files.py
+++ b/tools/continuous_build/clean_old_files.py
@@ -47,8 +47,11 @@ def delete_directory(directory):
     os.rmdir(directory)
     return True
   except OSError as exception:
-    # The directory probably contains newer files.
-    print "Could not remove directory %s: reason %s." % (directory, exception)
+    if "not empty" in str(exception):
+      # This is normal, ignore it
+      pass
+    else:
+      print "Could not remove directory %s: reason %s." % (directory, exception)
   return False