diff --git a/modules/system/boot/stage-1.nix b/modules/system/boot/stage-1.nix
index 1932599193e..9ad86312290 100644
--- a/modules/system/boot/stage-1.nix
+++ b/modules/system/boot/stage-1.nix
@@ -35,6 +35,14 @@ let
       '';
     };
 
+    boot.initrd.mdadmConf = mkOption {
+      default = "";
+      type = with types; string;
+      description = ''
+        Contents of /etc/mdadm.conf at initrd.
+      '';
+    };
+
     boot.initrd.preLVMCommands = mkOption {
       default = "";
       type = with types; string;
@@ -313,6 +321,9 @@ let
       [ { object = bootStage1;
           symlink = "/init";
         }
+        { object = pkgs.writeText "mdadm.conf" config.boot.initrd.mdadmConf;
+          symlink = "/etc/mdadm.conf";
+        }
       ] ++ optionals enableSplashScreen
         [ { object = extraUtils;
             suffix = "/bin/splash_helper";