diff --git a/compose/service.py b/compose/service.py
index ae4e7665c..f487db7d1 100644
--- a/compose/service.py
+++ b/compose/service.py
@@ -1806,7 +1806,7 @@ class _CLIBuilder(object):
                 line = p.stdout.readline()
                 if not line:
                     break
-                if line.startswith(magic_word):
+                if line.startswith(str(magic_word)):
                     appear = True
                 yield json.dumps({"stream": line})