diff --git a/deployment/check/common/deployerNode.nix b/deployment/check/common/deployerNode.nix
index 3aa13ba3..dccebf92 100644
--- a/deployment/check/common/deployerNode.nix
+++ b/deployment/check/common/deployerNode.nix
@@ -4,6 +4,7 @@
   pkgs,
   config,
   sources,
+  modulesPath,
   ...
 }:
 
@@ -73,17 +74,20 @@ in
           ## configuration and the store paths needed to build it and
           ## dump them in `system.extraDependencies`.
           machine =
-            (pkgs.nixos [
-              ./targetNode.nix
-              ../../../infra/common/nixos/repart.nix
-              config.system.extraDependenciesFromModule
-              {
-                nixpkgs.hostPlatform = "x86_64-linux";
-                _module.args = { inherit inputs sources; };
-                enableAcme = config.enableAcme;
-                acmeNodeIP = config.acmeNodeIP;
-              }
-            ]).config;
+            (pkgs.nixos (
+              [
+                ./targetNode.nix
+                ../../../infra/common/nixos/repart.nix
+                config.system.extraDependenciesFromModule
+                {
+                  nixpkgs.hostPlatform = "x86_64-linux";
+                  _module.args = { inherit inputs sources; };
+                  enableAcme = config.enableAcme;
+                  acmeNodeIP = config.acmeNodeIP;
+                }
+              ]
+              ++ (lib.optional config.useFlake "${modulesPath}/../lib/testing/nixos-test-base.nix")
+            )).config;
 
         in
         [
diff --git a/deployment/check/common/nixosTest.nix b/deployment/check/common/nixosTest.nix
index 9d4e528d..3da05084 100644
--- a/deployment/check/common/nixosTest.nix
+++ b/deployment/check/common/nixosTest.nix
@@ -4,6 +4,7 @@
   config,
   hostPkgs,
   sources,
+  modulesPath,
   ...
 }:
 
@@ -67,16 +68,19 @@ in
   };
 
   config = {
-    sourceFileset = fileset.unions [
-      # NOTE: not the flake itself; it will be overridden.
-      ../../../mkFlake.nix
-      ../../../flake.lock
-      ../../../npins
+    sourceFileset = fileset.unions (
+      [
+        # NOTE: not the flake itself; it will be overridden.
+        ../../../mkFlake.nix
+        ../../../flake.lock
+        ../../../npins
 
-      ./sharedOptions.nix
-      ./targetNode.nix
-      ./targetResource.nix
-    ];
+        ./sharedOptions.nix
+        ./targetNode.nix
+        ./targetResource.nix
+      ]
+      ++ (lib.optional config.useFlake "${modulesPath}/../lib/testing/nixos-test-base.nix")
+    );
 
     acmeNodeIP = config.nodes.acme.networking.primaryIPAddress;
 
@@ -112,7 +116,9 @@ in
         };
       })
       (genAttrs config.targetMachines (_: {
-        imports = [ ./targetNode.nix ];
+        imports = [
+          ./targetNode.nix
+        ] ++ (lib.optional config.useFlake (modulesPath + "/../lib/testing/nixos-test-base.nix"));
         _module.args = { inherit inputs sources; };
         enableAcme = config.enableAcme;
         acmeNodeIP = if config.enableAcme then config.nodes.acme.networking.primaryIPAddress else null;
diff --git a/deployment/check/common/targetNode.nix b/deployment/check/common/targetNode.nix
index dbf9ca3e..6f7e593b 100644
--- a/deployment/check/common/targetNode.nix
+++ b/deployment/check/common/targetNode.nix
@@ -16,8 +16,6 @@ in
 
   imports = [
     (modulesPath + "/profiles/qemu-guest.nix")
-    # FIXME needed for non-proxmox tests
-    # (modulesPath + "/../lib/testing/nixos-test-base.nix")
     ./sharedOptions.nix
   ];
 
diff --git a/deployment/check/common/targetResource.nix b/deployment/check/common/targetResource.nix
index 53e07f16..8b47270d 100644
--- a/deployment/check/common/targetResource.nix
+++ b/deployment/check/common/targetResource.nix
@@ -3,6 +3,7 @@
   lib,
   config,
   sources,
+  modulesPath,
   ...
 }:
 
@@ -39,7 +40,7 @@ in
       imports = [
         ./targetNode.nix
         (lib.modules.importJSON (config.pathToCwd + "/${config.nodeName}-network.json"))
-      ];
+      ] ++ (lib.optional config.useFlake "${modulesPath}/../lib/testing/nixos-test-base.nix");
 
       _module.args = { inherit inputs sources; };
       enableAcme = config.enableAcme;
diff --git a/deployment/check/data-model-nixops4/data-model.nix b/deployment/check/data-model-nixops4/data-model.nix
index 7ddbe3d9..d531cae7 100644
--- a/deployment/check/data-model-nixops4/data-model.nix
+++ b/deployment/check/data-model-nixops4/data-model.nix
@@ -41,7 +41,12 @@ in
                     inputs.nixops4-nixos.modules.nixops4Resource.nixos
                     ../common/targetResource.nix
                   ];
-                  nixos.module = mkNixosConfiguration environment required-resources;
+                  nixos.module = {
+                    imports = [
+                      (mkNixosConfiguration environment required-resources)
+                      "${sources.nixpkgs}/nixos/lib/testing/nixos-test-base.nix"
+                    ];
+                  };
                   _module.args = { inherit inputs sources; };
                   inherit nodeName pathToRoot pathFromRoot;
                 };
diff --git a/deployment/check/data-model-ssh/data-model.nix b/deployment/check/data-model-ssh/data-model.nix
index d3df53bf..3477ac7a 100644
--- a/deployment/check/data-model-ssh/data-model.nix
+++ b/deployment/check/data-model-ssh/data-model.nix
@@ -31,7 +31,12 @@ in
           }:
           {
             ssh-host = {
-              nixos-configuration = mkNixosConfiguration environment required-resources;
+              nixos-configuration = {
+                imports = [
+                  (mkNixosConfiguration environment required-resources)
+                  "${sources.nixpkgs}/nixos/lib/testing/nixos-test-base.nix"
+                ];
+              };
               system = targetSystem;
               ssh = {
                 username = "root";
diff --git a/deployment/check/data-model-tf/data-model.nix b/deployment/check/data-model-tf/data-model.nix
index a765fdc1..5dab2094 100644
--- a/deployment/check/data-model-tf/data-model.nix
+++ b/deployment/check/data-model-tf/data-model.nix
@@ -31,7 +31,12 @@ in
           }:
           {
             tf-host = {
-              nixos-configuration = mkNixosConfiguration environment required-resources;
+              nixos-configuration = {
+                imports = [
+                  (mkNixosConfiguration environment required-resources)
+                  "${sources.nixpkgs}/nixos/lib/testing/nixos-test-base.nix"
+                ];
+              };
               system = targetSystem;
               ssh = {
                 username = "root";