diff --git a/pkgs/tools/security/eid-viewer/default.nix b/pkgs/tools/security/eid-viewer/default.nix
index d33ad8fa5e51..45a314e13a6f 100644
--- a/pkgs/tools/security/eid-viewer/default.nix
+++ b/pkgs/tools/security/eid-viewer/default.nix
@@ -21,6 +21,10 @@ stdenv.mkDerivation rec {
 
   postInstall = ''
     wrapProgram $out/bin/eid-viewer --suffix LD_LIBRARY_PATH : ${pcsclite}/lib
+    cat >> $out/share/applications/eid-viewer.desktop << EOF
+    # eid-viewer creates XML without a header, making it "plain text":
+    MimeType=application/xml;text/xml;text/plain
+    EOF
   '';
 
   doCheck = true;