diff --git a/nixos/modules/services/x11/desktop-managers/kde4.nix b/nixos/modules/services/x11/desktop-managers/kde4.nix
index 3aa4821a052..f0de9120c69 100644
--- a/nixos/modules/services/x11/desktop-managers/kde4.nix
+++ b/nixos/modules/services/x11/desktop-managers/kde4.nix
@@ -87,6 +87,9 @@ in
 
 
   config = mkIf (xcfg.enable && cfg.enable) {
+    warnings = [
+      "KDE4 is long unmaintained and will be removed. Please update to KDE5."
+    ];
 
     # If KDE 4 is enabled, make it the default desktop manager (unless
     # overridden by the user's configuration).
diff --git a/nixos/modules/services/x11/display-managers/kdm.nix b/nixos/modules/services/x11/display-managers/kdm.nix
index 04701a1640c..bfb763f2858 100644
--- a/nixos/modules/services/x11/display-managers/kdm.nix
+++ b/nixos/modules/services/x11/display-managers/kdm.nix
@@ -35,7 +35,7 @@ let
       ${optionalString (cfg.setupScript != "")
       ''
         Setup=${cfg.setupScript}
-      ''} 
+      ''}
 
       [X-*-Greeter]
       HiddenUsers=root,${concatStringsSep "," dmcfg.hiddenUsers}
@@ -128,6 +128,9 @@ in
   ###### implementation
 
   config = mkIf cfg.enable {
+    warnings = [
+      "KDM is long unmaintained and will be removed. Please update to SDDM."
+    ];
 
     services.xserver.displayManager.slim.enable = false;