diff --git a/songbook_core/build.py b/songbook_core/build.py
index 634e3bfa..850bb833 100644
--- a/songbook_core/build.py
+++ b/songbook_core/build.py
@@ -212,7 +212,7 @@ class SongbookBuilder(object):
                 self.build_sbx()
             elif step == 'clean':
                 self.clean()
-            elif step.startswith("%"):
+            elif step.startswith("#"):
                 self.build_custom(step[1:])
             else:
                 # Unknown step name