diff --git a/bin/testcode.py b/bin/testcode.py
index 3b7ce13..3b01805 100755
--- a/bin/testcode.py
+++ b/bin/testcode.py
@@ -351,7 +351,7 @@ def run_test_worker(semaphore, semaphore_lock, tests, *run_test_args):
         # patterns in the output file--otherwise we can't figure out which
         # output file belongs to which test.  We might be able to for some
         # wildcards, but let's err on the side of caution.
-        wildcards = re.compile('.*(\*|\?|\[.*\]).*')
+        wildcards = re.compile(r'.*(\*|\?|\[.*\]).*')
         serialized_tests = []
         test_store = {}
         for test in tests: