diff --git a/bin/pungi-config-dump b/bin/pungi-config-dump
index c1b3fab8..ec9e5659 100755
--- a/bin/pungi-config-dump
+++ b/bin/pungi-config-dump
@@ -64,6 +64,7 @@ def main():
         "-e",
         "--define",
         action="append",
+        default=[],
         metavar="VAR=VALUE",
         type=validate_definition,
         help=(