diff --git a/.gitmodules b/.gitmodules
index 01dcc40..d108718 100644
--- a/.gitmodules
+++ b/.gitmodules
@@ -1,6 +1,7 @@
 [submodule "calendar"]
 	path = calendar
 	url = https://github.com/nextcloud/calendar.git
+	branch = main
 [submodule "server"]
 	path = server
 	url = https://github.com/nextcloud/server.git
diff --git a/.vscode/launch.json b/.vscode/launch.json
index eb9bf8f..29a4231 100644
--- a/.vscode/launch.json
+++ b/.vscode/launch.json
@@ -12,6 +12,9 @@
             "pathMappings": {
                 "/var/lib/nextcloud/server/3rdparty/sabre/dav": "${workspaceRoot}/dav",
                 "/var/lib/nextcloud/server/3rdparty/sabre/vobject": "${workspaceRoot}/vobject",
+                "/var/lib/nextcloud/server": "${workspaceRoot}/server",
+                "/var/lib/nextcloud/server/apps/dav": "${workspaceRoot}/server/apps/dav",
+
             },              
         }
     ]
diff --git a/Makefile b/Makefile
index 4b53abb..1bf0b85 100644
--- a/Makefile
+++ b/Makefile
@@ -1,10 +1,11 @@
 build:
-	git submodule update --init
+	git submodule update --remote --init
 	# Build server
 	cd server && git submodule update --init
 	cd server && make dev-setup
 	cd server && make build-js
 	cd server && npm run sass
+	# config ⇒ /var/lib/nextcloud/config # FIXME
 	cd calendar && make dev-setup
 	cd calendar && make build-js
 
diff --git a/calendar b/calendar
index ac58a9b..7f818aa 160000
--- a/calendar
+++ b/calendar
@@ -1 +1 @@
-Subproject commit ac58a9b16e4c9c24a42333bc2a76a63b159ca96e
+Subproject commit 7f818aaa46935bf57c6988a0b6577ef9179c9db7
diff --git a/dav b/dav
index 00cf16c..2106db0 160000
--- a/dav
+++ b/dav
@@ -1 +1 @@
-Subproject commit 00cf16c6553bf09e914d0b0aa1c3e2d08533d326
+Subproject commit 2106db0eed5dea58e294712a54413bd451a54252
diff --git a/server b/server
index 21254b0..ad00a14 160000
--- a/server
+++ b/server
@@ -1 +1 @@
-Subproject commit 21254b02ebe696ba1028ae91180e21d797061f00
+Subproject commit ad00a149ea2bb262e62fbecf11051fd035f90ec4
diff --git a/vm-nextcloud.nix b/vm-nextcloud.nix
index 87a3d90..5f68cff 100644
--- a/vm-nextcloud.nix
+++ b/vm-nextcloud.nix
@@ -37,10 +37,15 @@
     enable = true;
     package = pkgs.nextcloud25;
     hostName = "localhost";
+    extraApps = with pkgs.nextcloud25Packages.apps; {
+      inherit calendar;
+    };
+    extraAppsEnable = true;
     config = {
       adminuser = "admin";
       adminpassFile = "${pkgs.writeText "adminpass" "test123"}";
     };
+    caching.apcu = false;
     phpPackage = lib.mkForce (pkgs.php.buildEnv {
       extensions = ({ enabled, all }: enabled ++ (with all; [
         xdebug
@@ -60,6 +65,18 @@
       debug = true;
       logLevel = 0;
       trusted_domains = [ "10.100.100.1" ];
+      apps_paths = [
+        {
+          path = "/var/lib/nextcloud/nix-apps";
+          url = "/nix-apps";
+          writeable = false;
+        }
+        {
+          path = "/var/lib/nextcloud/server/apps";
+          url = "/apps";
+          writeable = false;
+        }
+      ];
     };
   };
   # Mount our local development repositories into the VM
@@ -68,10 +85,11 @@
       target = ./server;
       cache = "none";
     };
-    "/var/lib/nextcloud/store-apps/calendar" = {
-       target = ./calendar;
-       cache = "none";
-    };
+    # FIXME
+    #"/var/lib/nextcloud/server/apps/calendar" = {
+    #   target = ./calendar;
+    #   cache = "none";
+    #};
     "/var/lib/nextcloud/server/3rdparty/sabre/dav" = {
        target = ./dav;
        cache = "none";