diff --git a/pkgs/applications/networking/mailreaders/thunderbird/68.nix b/pkgs/applications/networking/mailreaders/thunderbird/68.nix
index ee5b7c5e17b..60dc1205484 100644
--- a/pkgs/applications/networking/mailreaders/thunderbird/68.nix
+++ b/pkgs/applications/networking/mailreaders/thunderbird/68.nix
@@ -4,6 +4,7 @@
 , bzip2
 , cargo
 , common-updater-scripts
+, copyDesktopItems
 , coreutils
 , curl
 , dbus
@@ -83,6 +84,7 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [
     autoconf213
     cargo
+    copyDesktopItems
     gnused
     llvmPackages.llvm
     m4
@@ -262,8 +264,8 @@ stdenv.mkDerivation rec {
 
   doCheck = false;
 
-  postInstall = let
-    desktopItem = makeDesktopItem {
+  desktopItems = [
+    (makeDesktopItem {
       categories = lib.concatStringsSep ";" [ "Application" "Network" ];
       desktopName = "Thunderbird";
       genericName = "Mail Reader";
@@ -283,12 +285,11 @@ stdenv.mkDerivation rec {
         "x-scheme-handler/snews"
         "x-scheme-handler/nntp"
       ];
-    };
-  in ''
+    })
+  ];
+  postInstall = ''
     # TODO: Move to a dev output?
     rm -rf $out/include $out/lib/thunderbird-devel-* $out/share/idl
-
-    ${desktopItem.buildCommand}
   '';
 
   preFixup = ''
diff --git a/pkgs/applications/networking/mailreaders/thunderbird/default.nix b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
index 8295e8dbc87..8f4c96bbbcf 100644
--- a/pkgs/applications/networking/mailreaders/thunderbird/default.nix
+++ b/pkgs/applications/networking/mailreaders/thunderbird/default.nix
@@ -2,6 +2,7 @@
 , bzip2
 , cargo
 , common-updater-scripts
+, copyDesktopItems
 , coreutils
 , curl
 , dbus
@@ -82,6 +83,7 @@ stdenv.mkDerivation rec {
   nativeBuildInputs = [
     autoconf213
     cargo
+    copyDesktopItems
     gnused
     llvmPackages.llvm
     m4
@@ -257,8 +259,8 @@ stdenv.mkDerivation rec {
 
   doCheck = false;
 
-  postInstall = let
-    desktopItem = makeDesktopItem {
+  desktopItems = [
+    (makeDesktopItem {
       categories = lib.concatStringsSep ";" [ "Application" "Network" ];
       desktopName = "Thunderbird";
       genericName = "Mail Reader";
@@ -278,12 +280,12 @@ stdenv.mkDerivation rec {
         "x-scheme-handler/snews"
         "x-scheme-handler/nntp"
       ];
-    };
-  in ''
+    })
+  ];
+
+  postInstall = ''
     # TODO: Move to a dev output?
     rm -rf $out/include $out/lib/thunderbird-devel-* $out/share/idl
-
-    ${desktopItem.buildCommand}
   '';
 
   preFixup = ''