diff --git a/pkgs/by-name/gj/gjs/disable-umlaut-test.patch b/pkgs/by-name/gj/gjs/disable-umlaut-test.patch
new file mode 100644
index 000000000000..b4f4be0f16aa
--- /dev/null
+++ b/pkgs/by-name/gj/gjs/disable-umlaut-test.patch
@@ -0,0 +1,13 @@
+diff --git a/installed-tests/js/testGIMarshalling.js b/installed-tests/js/testGIMarshalling.js
+index b94aa7c8..8f79fe71 100644
+--- a/installed-tests/js/testGIMarshalling.js
++++ b/installed-tests/js/testGIMarshalling.js
+@@ -2931,7 +2931,7 @@ describe('Filename tests', function () {
+     });
+ 
+     it('various types of path existing', function () {
+-        const paths = ['foo-2', 'öäü-3'];
++        const paths = ['foo-2'];
+         for (const path of paths) {
+             const file = workdir.get_child(path);
+             const stream = file.create(Gio.FileCreateFlags.NONE, null);
diff --git a/pkgs/by-name/gj/gjs/package.nix b/pkgs/by-name/gj/gjs/package.nix
index 691575c5a93c..f9b1f3c1ffa3 100644
--- a/pkgs/by-name/gj/gjs/package.nix
+++ b/pkgs/by-name/gj/gjs/package.nix
@@ -64,6 +64,12 @@ stdenv.mkDerivation (finalAttrs: {
     # Disable introspection test in installed tests
     # (minijasmine:1317): GLib-GIO-WARNING **: 17:33:39.556: Error creating IO channel for /proc/self/mountinfo: No such file or directory (g-io-error-quark, 1)
     ./disable-introspection-test.patch
+
+    # The reason is unclear, but a test that creates a file named "öäü-3" fails only on ZFS filesystems:
+    # 24/78 gjs:JS / GIMarshalling  FAIL  0.59s  726/727 subtests passed
+    # not ok 796 Filename tests various types of path existing
+    # Message: Error opening file “/build/.UGHEA3/öäü-3”: Invalid or incomplete multibyte or wide character in /build/gjs-1.84.2/build/../installed-tests/js/testGIMarshalling.js (line 2937)
+    ./disable-umlaut-test.patch
   ];
 
   nativeBuildInputs = [