diff --git a/manifests/source.pp b/manifests/source.pp
index 7a44221497..d3862f281c 100644
--- a/manifests/source.pp
+++ b/manifests/source.pp
@@ -108,7 +108,7 @@
   Boolean $enabled = true, # deb822
   Enum['present', 'absent'] $ensure = present,
   Optional[Variant[String[0], Array[String[0]]]] $release = undef,
-  Variant[String[1], Array[String[1]]] $repos = 'main',
+  Optional[Variant[String[1], Array[String[1]]]] $repos = 'main',
   Hash $include = {},
   Optional[Variant[String[1], Hash]] $key = undef,
   Optional[Stdlib::AbsolutePath] $keyring = undef,