diff --git a/endpoints/api/build.py b/endpoints/api/build.py
index 0b2ef5464..b64f3ad37 100644
--- a/endpoints/api/build.py
+++ b/endpoints/api/build.py
@@ -273,10 +273,12 @@ class RepositoryBuildList(RepositoryParamResource):
 
     # Start the build.
     repo = model.repository.get_repository(namespace, repository)
+    if repo is None:
+      raise NotFound()
 
-    build_name =  (user_files.get_file_checksum(dockerfile_id)
-                    if dockerfile_id
-                    else hashlib.sha224(archive_url).hexdigest()[0:7])
+    build_name = (user_files.get_file_checksum(dockerfile_id)
+                  if dockerfile_id
+                  else hashlib.sha224(archive_url).hexdigest()[0:7])
 
     prepared = PreparedBuild()
     prepared.build_name = build_name
@@ -317,6 +319,9 @@ class RepositoryBuildResource(RepositoryParamResource):
     except model.build.InvalidRepositoryBuildException:
       raise NotFound()
 
+    if build.repository.name != repository or build.repository.namespace_user.username != namespace:
+      raise NotFound()
+
     return build_status_view(build)
 
   @require_repo_admin