diff --git a/build_artifact.py b/build_artifact.py
index fb62773..473bfb0 100755
--- a/build_artifact.py
+++ b/build_artifact.py
@@ -623,7 +623,7 @@
 
 
 _AddCrOSArtifact(artifact_info.FULL_PAYLOAD, AUTestPayload,
-                 '.*full.*bin(\.json)?\\Z', is_regex_name=True)
+                 r'.*full.*bin(\.json)?\Z', is_regex_name=True)
 
 
 class DeltaPayloadNtoN(DeltaPayloadBase):