diff --git a/nixos/modules/installer/cd-dvd/iso-image.nix b/nixos/modules/installer/cd-dvd/iso-image.nix
index 3ff1b3d670e9..860e240b43d4 100644
--- a/nixos/modules/installer/cd-dvd/iso-image.nix
+++ b/nixos/modules/installer/cd-dvd/iso-image.nix
@@ -91,29 +91,9 @@ let
     SERIAL 0 115200
     TIMEOUT ${builtins.toString syslinuxTimeout}
     UI vesamenu.c32
-    MENU TITLE NixOS
     MENU BACKGROUND /isolinux/background.png
-    MENU RESOLUTION 800 600
-    MENU CLEAR
-    MENU ROWS 6
-    MENU CMDLINEROW -4
-    MENU TIMEOUTROW -3
-    MENU TABMSGROW  -2
-    MENU HELPMSGROW -1
-    MENU HELPMSGENDROW -1
-    MENU MARGIN 0
 
-    #                                FG:AARRGGBB  BG:AARRGGBB   shadow
-    MENU COLOR BORDER       30;44      #00000000    #00000000   none
-    MENU COLOR SCREEN       37;40      #FF000000    #00E2E8FF   none
-    MENU COLOR TABMSG       31;40      #80000000    #00000000   none
-    MENU COLOR TIMEOUT      1;37;40    #FF000000    #00000000   none
-    MENU COLOR TIMEOUT_MSG  37;40      #FF000000    #00000000   none
-    MENU COLOR CMDMARK      1;36;40    #FF000000    #00000000   none
-    MENU COLOR CMDLINE      37;40      #FF000000    #00000000   none
-    MENU COLOR TITLE        1;36;44    #00000000    #00000000   none
-    MENU COLOR UNSEL        37;44      #FF000000    #00000000   none
-    MENU COLOR SEL          7;37;40    #FFFFFFFF    #FF5277C3   std
+    ${config.isoImage.syslinuxTheme}
 
     DEFAULT boot
 
@@ -601,6 +581,37 @@ in
       '';
     };
 
+    isoImage.syslinuxTheme = mkOption {
+      default = ''
+        MENU TITLE NixOS
+        MENU RESOLUTION 800 600
+        MENU CLEAR
+        MENU ROWS 6
+        MENU CMDLINEROW -4
+        MENU TIMEOUTROW -3
+        MENU TABMSGROW  -2
+        MENU HELPMSGROW -1
+        MENU HELPMSGENDROW -1
+        MENU MARGIN 0
+
+        #                                FG:AARRGGBB  BG:AARRGGBB   shadow
+        MENU COLOR BORDER       30;44      #00000000    #00000000   none
+        MENU COLOR SCREEN       37;40      #FF000000    #00E2E8FF   none
+        MENU COLOR TABMSG       31;40      #80000000    #00000000   none
+        MENU COLOR TIMEOUT      1;37;40    #FF000000    #00000000   none
+        MENU COLOR TIMEOUT_MSG  37;40      #FF000000    #00000000   none
+        MENU COLOR CMDMARK      1;36;40    #FF000000    #00000000   none
+        MENU COLOR CMDLINE      37;40      #FF000000    #00000000   none
+        MENU COLOR TITLE        1;36;44    #00000000    #00000000   none
+        MENU COLOR UNSEL        37;44      #FF000000    #00000000   none
+        MENU COLOR SEL          7;37;40    #FFFFFFFF    #FF5277C3   std
+      '';
+      type = types.str;
+      description = ''
+        The syslinux theme used for BIOS boot.
+      '';
+    };
+
     isoImage.appendToMenuLabel = mkOption {
       default = " Installer";
       example = " Live System";