diff --git a/modules/misc/fontconfig.nix b/modules/misc/fontconfig.nix
index 4a600dd1e..0f4d38fb5 100644
--- a/modules/misc/fontconfig.nix
+++ b/modules/misc/fontconfig.nix
@@ -72,11 +72,13 @@ in
         type = lib.types.bool;
         default = false;
         description = ''
-          Whether to enable fontconfig configuration. This will, for
-          example, allow fontconfig to discover fonts and
-          configurations installed through
-          {var}`home.packages` and
-          {command}`nix-env`.
+          Whether to enable fontconfig configuration. This will, for example,
+          allow fontconfig to discover fonts and configurations installed through
+          {var}`home.packages` and {command}`nix-env`.
+
+          If Home Manager is installed as a NixOS submodule and
+          {var}`home-manager.useUserPackages` is enabled, this option defaults to the
+          value of NixOS' {var}`fonts.fontconfig.enable`.
         '';
       };
 
diff --git a/nixos/default.nix b/nixos/default.nix
index 9d6dc7cec..51ee84ce7 100644
--- a/nixos/default.nix
+++ b/nixos/default.nix
@@ -79,6 +79,9 @@ in
             config = {
               # The per-user directory inside /etc/profiles is not known by
               # fontconfig by default.
+              #
+              # When changing the following line, remember to reflect these
+              # changes in the description of 'fonts.fontconfig.enable'!
               fonts.fontconfig.enable = lib.mkDefault (cfg.useUserPackages && config.fonts.fontconfig.enable);
 
               # Inherit glibcLocales setting from NixOS.