diff --git a/flake.lock b/flake.lock
index 13482c4f..6d239faa 100644
--- a/flake.lock
+++ b/flake.lock
@@ -81,7 +81,7 @@
         "utils": "utils_2"
       },
       "locked": {
-        "narHash": "sha256-clwJnNLVOASak2CfkWu3Yztb1uWwtndY4VLDWEa9R3s=",
+        "narHash": "sha256-TOrVXGFk5rt1Wn14ja2spg44NuZnFM/V6qguQfO+8Kc=",
         "path": "./lib",
         "type": "path"
       },
@@ -355,11 +355,11 @@
         "flake-utils": "flake-utils"
       },
       "locked": {
-        "lastModified": 1619480667,
-        "narHash": "sha256-KBiMpZcCv7D3wQ51ow7Sq8Xl01hDiRp5f7Py93CeD40=",
+        "lastModified": 1619532520,
+        "narHash": "sha256-+xIFAW5J0AcxwAflAX1gg/C8kfaqeZbS4XAZusCrZPY=",
         "owner": "gytis-ivaskevicius",
         "repo": "flake-utils-plus",
-        "rev": "be032a4396ad4cd7ea9bb733db8e456ec339ac9c",
+        "rev": "8eb7f9206713a528174c20c5133521dc37e2bfb1",
         "type": "github"
       },
       "original": {
diff --git a/lib/flake.lock b/lib/flake.lock
index eda785b8..ebf5e6d3 100644
--- a/lib/flake.lock
+++ b/lib/flake.lock
@@ -146,11 +146,11 @@
         "flake-utils": "flake-utils"
       },
       "locked": {
-        "lastModified": 1619480667,
-        "narHash": "sha256-KBiMpZcCv7D3wQ51ow7Sq8Xl01hDiRp5f7Py93CeD40=",
+        "lastModified": 1619532520,
+        "narHash": "sha256-+xIFAW5J0AcxwAflAX1gg/C8kfaqeZbS4XAZusCrZPY=",
         "owner": "gytis-ivaskevicius",
         "repo": "flake-utils-plus",
-        "rev": "be032a4396ad4cd7ea9bb733db8e456ec339ac9c",
+        "rev": "8eb7f9206713a528174c20c5133521dc37e2bfb1",
         "type": "github"
       },
       "original": {
diff --git a/lib/mkFlake/default.nix b/lib/mkFlake/default.nix
index bcab7a13..7b12cf41 100644
--- a/lib/mkFlake/default.nix
+++ b/lib/mkFlake/default.nix
@@ -25,35 +25,39 @@ let
     })
   ];
 
+  stripChannel = channel: removeAttrs channel [
+    # arguments in our channels api that shouldn't be passed to fup
+    "overlays"
+  ];
   getDefaultChannel = channels: channels.${cfg.nixos.hostDefaults.channelName};
+
+  # evalArgs sets channelName and system to null by default
+  # but for proper default handling in fup, null args have to be removed
+  stripHost = args: removeAttrs (lib.filterAttrs (_: arg: arg != null) args) [
+    # arguments in our hosts/hostDefaults api that shouldn't be passed to fup
+    "externalModules"
+  ];
+  hosts = lib.mapAttrs (_: stripHost) cfg.nixos.hosts;
+  hostDefaults = stripHost cfg.nixos.hostDefaults;
 in
 lib.systemFlake (lib.recursiveUpdate
   otherArguments
   {
-    inherit self inputs;
+    inherit self inputs hosts;
     inherit (cfg) channelsConfig supportedSystems;
 
     channels = mapAttrs
       (name: channel:
-        channel // {
+        stripChannel (channel // {
           # pass channels if "overlay" has three arguments
           overlaysBuilder = channels: lib.unifyOverlays channels channel.overlays;
-        }
+        })
       ) cfg.channels;
 
-    # the host arguments cannot exist for fup hostDefaults to work
-    # so evalArgs sets them to null by default and the null args are filtered out here
-    hosts = mapAttrs (_: host: lib.filterAttrs (_: arg: arg != null) host) cfg.nixos.hosts;
-
-    hostDefaults = {
+    hostDefaults = lib.mergeAny hostDefaults {
       specialArgs.suites = cfg.nixos.suites;
-      modules = cfg.nixos.hostDefaults.modules
-        ++ cfg.nixos.hostDefaults.externalModules
-        ++ defaultModules;
+      modules = cfg.nixos.hostDefaults.externalModules ++ defaultModules;
       builder = os.devosSystem { inherit self inputs; };
-      inherit (cfg.nixos.hostDefaults)
-        channelName
-        system;
     };
 
     nixosModules = lib.exporter.modulesFromList cfg.nixos.hostDefaults.modules;