diff --git a/modules/misc/dconf.nix b/modules/misc/dconf.nix
index e75b30972..ef03a1fc6 100644
--- a/modules/misc/dconf.nix
+++ b/modules/misc/dconf.nix
@@ -80,7 +80,9 @@ in
     (lib.mkIf cfg.enable {
       home.packages = [ pkgs.dconf ];
       dbus.packages = [ pkgs.dconf ];
-      home.sessionVariables.GIO_EXTRA_MODULES = "${pkgs.dconf.lib}/lib/gio/modules";
+      home.sessionVariablesExtra = ''
+        export GIO_EXTRA_MODULES="${pkgs.dconf.lib}/lib/gio/modules''${GIO_EXTRA_MODULES:+:}$GIO_EXTRA_MODULES"
+      '';
     })
     (lib.mkIf (cfg.enable && cfg.settings != { }) {
       # Make sure the dconf directory exists.
diff --git a/tests/modules/home-environment/session-variables.nix b/tests/modules/home-environment/session-variables.nix
index 9e01bb94a..19b65f79c 100644
--- a/tests/modules/home-environment/session-variables.nix
+++ b/tests/modules/home-environment/session-variables.nix
@@ -9,7 +9,6 @@ let
     if [ -n "$__HM_SESS_VARS_SOURCED" ]; then return; fi
     export __HM_SESS_VARS_SOURCED=1
 
-    export GIO_EXTRA_MODULES="${pkgs.dconf}/lib/gio/modules"
     export LOCALE_ARCHIVE_2_27="${config.i18n.glibcLocales}/lib/locale/locale-archive"
     export V1="v1"
     export V2="v2-v1"
@@ -18,6 +17,7 @@ let
     export XDG_DATA_HOME="/home/hm-user/.local/share"
     export XDG_STATE_HOME="/home/hm-user/.local/state"
 
+    export GIO_EXTRA_MODULES="${pkgs.dconf}/lib/gio/modules''${GIO_EXTRA_MODULES:+:}$GIO_EXTRA_MODULES"
   '';
 
   darwinExpected = ''