diff --git a/deployment/data-model.nix b/deployment/data-model.nix
index 6e7389bc..4e1f910a 100644
--- a/deployment/data-model.nix
+++ b/deployment/data-model.nix
@@ -151,7 +151,10 @@ in
               };
               implementation = mkOption {
                 description = "Mapping of resources required by applications to available resources; the result can be deployed";
-                type = environment.config.resource-mapping.function-type;
+                type = functionTo (submoduleWith {
+                  class = "nixops4Deployment";
+                  modules = [ environment.config.resource-mapping.output-type ];
+                });
               };
               resource-mapping = mkOption {
                 description = "Function type for the mapping from resources to a (NixOps4) deployment";