diff --git a/nixos/modules/services/development/hoogle.nix b/nixos/modules/services/development/hoogle.nix
index a661e3acae3e..6d6c88b9b2aa 100644
--- a/nixos/modules/services/development/hoogle.nix
+++ b/nixos/modules/services/development/hoogle.nix
@@ -25,6 +25,7 @@ in {
     };
 
     packages = mkOption {
+      type = types.functionTo (types.listOf types.package);
       default = hp: [];
       defaultText = "hp: []";
       example = "hp: with hp; [ text lens ]";
diff --git a/nixos/modules/services/misc/gitit.nix b/nixos/modules/services/misc/gitit.nix
index 1ec030549f98..f09565283f3c 100644
--- a/nixos/modules/services/misc/gitit.nix
+++ b/nixos/modules/services/misc/gitit.nix
@@ -42,6 +42,7 @@ let
       };
 
       extraPackages = mkOption {
+        type = types.functionTo (types.listOf types.package);
         default = self: [];
         example = literalExample ''
           haskellPackages: [
diff --git a/nixos/modules/services/misc/ihaskell.nix b/nixos/modules/services/misc/ihaskell.nix
index 684a242d7385..c7332b87803a 100644
--- a/nixos/modules/services/misc/ihaskell.nix
+++ b/nixos/modules/services/misc/ihaskell.nix
@@ -21,6 +21,7 @@ in
       };
 
       extraPackages = mkOption {
+        type = types.functionTo (types.listOf types.package);
         default = self: [];
         example = literalExample ''
           haskellPackages: [
diff --git a/nixos/modules/services/misc/octoprint.nix b/nixos/modules/services/misc/octoprint.nix
index a69e65073050..5a64946f9f63 100644
--- a/nixos/modules/services/misc/octoprint.nix
+++ b/nixos/modules/services/misc/octoprint.nix
@@ -66,6 +66,7 @@ in
       };
 
       plugins = mkOption {
+        type = types.functionTo (types.listOf types.package);
         default = plugins: [];
         defaultText = "plugins: []";
         example = literalExample "plugins: with plugins; [ themeify stlviewer ]";
diff --git a/nixos/modules/services/monitoring/netdata.nix b/nixos/modules/services/monitoring/netdata.nix
index db51fdbd2c61..d5b679097b30 100644
--- a/nixos/modules/services/monitoring/netdata.nix
+++ b/nixos/modules/services/monitoring/netdata.nix
@@ -77,6 +77,7 @@ in {
           '';
         };
         extraPackages = mkOption {
+          type = types.functionTo (types.listOf types.package);
           default = ps: [];
           defaultText = "ps: []";
           example = literalExample ''
diff --git a/nixos/modules/services/networking/supybot.nix b/nixos/modules/services/networking/supybot.nix
index 864c3319c547..332c3ced06f0 100644
--- a/nixos/modules/services/networking/supybot.nix
+++ b/nixos/modules/services/networking/supybot.nix
@@ -64,6 +64,7 @@ in
       };
 
       extraPackages = mkOption {
+        type = types.functionTo (types.listOf types.package);
         default = p: [];
         description = ''
           Extra Python packages available to supybot plugins. The
diff --git a/nixos/modules/services/x11/window-managers/exwm.nix b/nixos/modules/services/x11/window-managers/exwm.nix
index 3e97d28d83b5..0743f35c1d31 100644
--- a/nixos/modules/services/x11/window-managers/exwm.nix
+++ b/nixos/modules/services/x11/window-managers/exwm.nix
@@ -37,6 +37,7 @@ in
         description = "Enable an uncustomised exwm configuration.";
       };
       extraPackages = mkOption {
+        type = types.functionTo (types.listOf types.package);
         default = self: [];
         example = literalExample ''
           epkgs: [
diff --git a/nixos/modules/services/x11/window-managers/xmonad.nix b/nixos/modules/services/x11/window-managers/xmonad.nix
index 2bb4827be9d5..fe8ed3812511 100644
--- a/nixos/modules/services/x11/window-managers/xmonad.nix
+++ b/nixos/modules/services/x11/window-managers/xmonad.nix
@@ -53,6 +53,7 @@ in {
       };
 
       extraPackages = mkOption {
+        type = types.functionTo (types.listOf types.package);
         default = self: [];
         defaultText = "self: []";
         example = literalExample ''