diff --git a/nixos/modules/services/x11/display-managers/default.nix b/nixos/modules/services/x11/display-managers/default.nix
index 7fc8db95a485c..ca8ed8f95b685 100644
--- a/nixos/modules/services/x11/display-managers/default.nix
+++ b/nixos/modules/services/x11/display-managers/default.nix
@@ -216,6 +216,7 @@ in
       };
 
       session = mkOption {
+        type = with types; listOf attrs;
         default = [];
         example = literalExpression
           ''