diff --git a/deployment/data-model.nix b/deployment/data-model.nix
index c3d5d53a..5df56959 100644
--- a/deployment/data-model.nix
+++ b/deployment/data-model.nix
@@ -15,7 +15,7 @@ let
     functionTo
     ;
 
-  functionType = import ./function.nix;
+  functionType = submodule ./function.nix;
   application-resources = submodule {
     options.resources = mkOption {
       # TODO: maybe transpose, and group the resources by type instead
@@ -110,7 +110,7 @@ in
             # TODO(@fricklerhandwerk): this needs a better name, it's just the type
             config-mapping = mkOption {
               description = "Function type for the mapping from application configuration to required resources";
-              type = submodule functionType;
+              type = functionType;
               readOnly = true;
               default = {
                 input-type = submodule application.config.module;
@@ -146,7 +146,7 @@ in
             };
             resource-mapping = mkOption {
               description = "Function type for the mapping from resources to a (NixOps4) deployment";
-              type = submodule functionType;
+              type = functionType;
               readOnly = true;
               default = {
                 input-type = application-resources;