diff --git a/modules/installer/cd-dvd/installation-cd-base.nix b/modules/installer/cd-dvd/installation-cd-base.nix
index 2f7a44863c6..3a4f2965d00 100644
--- a/modules/installer/cd-dvd/installation-cd-base.nix
+++ b/modules/installer/cd-dvd/installation-cd-base.nix
@@ -75,6 +75,11 @@ in
       ./memtest.nix
       ./iso-image.nix
       ../../profiles/base.nix
+
+      # Enable devices which are usually scanned, because we don't know the
+      # target system.
+      ../scan/detected.nix
+      ../scan/not-detected.nix
     ];
 
   # ISO naming.
@@ -134,11 +139,6 @@ in
       }
     '';
 
-  # Include the firmware for various wireless cards.
-  networking.enableRT73Firmware = true;
-  networking.enableIntel2200BGFirmware = true;
-  networking.enableIntel3945ABGFirmware = true;
-
   # To speed up installation a little bit, include the complete stdenv
   # in the Nix store on the CD.
   isoImage.storeContents = [ pkgs.stdenv pkgs.klibc pkgs.klibcShrunk ];
diff --git a/modules/installer/scan/detected.nix b/modules/installer/scan/detected.nix
new file mode 100644
index 00000000000..09d04608e68
--- /dev/null
+++ b/modules/installer/scan/detected.nix
@@ -0,0 +1,13 @@
+# List all devices which are detected by nixos-hardware-scan.
+# Common devices are enabled by default.
+{config, pkgs, ...}:
+
+with pkgs.lib;
+
+{
+  config = mkDefault {
+    # Wireless card firmware
+    networking.enableIntel2200BGFirmware = true;
+    networking.enableIntel3945ABGFirmware = true;
+  };
+}
diff --git a/modules/installer/scan/not-detected.nix b/modules/installer/scan/not-detected.nix
new file mode 100644
index 00000000000..3a4a7f40fc6
--- /dev/null
+++ b/modules/installer/scan/not-detected.nix
@@ -0,0 +1,12 @@
+# List all devices which are _not_ detected by nixos-hardware-scan.
+# Common devices are enabled by default.
+{config, pkgs, ...}:
+
+with pkgs.lib;
+
+{
+  config = mkDefault {
+    # Wireless card firmware
+    networking.enableRT73Firmware = true;
+  };
+}
diff --git a/modules/installer/tools/nixos-hardware-scan.pl b/modules/installer/tools/nixos-hardware-scan.pl
index ce1085f8ebc..25ef0afe67a 100644
--- a/modules/installer/tools/nixos-hardware-scan.pl
+++ b/modules/installer/tools/nixos-hardware-scan.pl
@@ -227,7 +227,13 @@ my $attrs = multiLineList("  ", removeDups @attrs);
 print <<EOF ;
 # This is a generated file.  Do not modify!
 # Make changes to /etc/nixos/configuration.nix instead.
+{modulesPath, ...}:
+
 {
+  require = [
+    "\${modulesPath}/installer/scan/not-detected.nix"
+  ];
+
   boot.initrd.kernelModules = [ $initrdKernelModules ];
   boot.kernelModules = [ $kernelModules ];