diff --git a/outputs.nix b/outputs.nix
index c87b806..72176b3 100644
--- a/outputs.nix
+++ b/outputs.nix
@@ -15,7 +15,7 @@ in (utils.lib.eachSystem (builtins.filter filter_system utils.lib.defaultSystems
     pkgs-unstable = nixpkgs-unstable.legacyPackages."${system}";
     pkgs = nixpkgs.legacyPackages."${system}";
 
-    vmMicroVMOverwrites = options: {
+    vmMicroVMOverwrites = hostname: options: {
       microvm = {
         mem = pkgs.lib.mkForce 4096;
         hypervisor = pkgs.lib.mkForce "qemu";
@@ -43,9 +43,12 @@ in (utils.lib.eachSystem (builtins.filter filter_system utils.lib.defaultSystems
 
       fileSystems = {
         "/".fsType = pkgs.lib.mkForce "tmpfs";
-        "/var/lib" = pkgs.lib.mkIf (options.varPath != "") {
-          depends = [ "/var" ];
-        };
+
+        # prometheus uses a memory mapped file which doesnt seem supported by 9p shares
+        # therefore we mount a tmpfs inside the datadir
+        "/var/lib/prometheus2/data" = pkgs.lib.mkIf (hostname == "overwatch" && options.varPath != "") (pkgs.lib.mkForce {
+          fsType = pkgs.lib.mkForce "tmpfs";
+        });
       };
 
       boot.isContainer = pkgs.lib.mkForce false;