diff --git a/gio/gcontenttype.c b/gio/gcontenttype.c
index 8d81f5fa1..de9e5a739 100644
--- a/gio/gcontenttype.c
+++ b/gio/gcontenttype.c
@@ -1274,7 +1274,7 @@ component_match (Enumerator  *e,
                  gint         depth,
                  const gchar *name)
 {
-  gchar *case_folded, *key;
+  gchar *case_folded, *key, *utf8_name;
   gboolean found;
 
   if (strcmp (name, e->components[depth]) == 0)
@@ -1283,11 +1283,16 @@ component_match (Enumerator  *e,
   if (!e->ignore_case)
     return FALSE;
 
-  case_folded = g_utf8_casefold (name, -1);
+  utf8_name = g_filename_to_utf8 (name, -1, NULL, NULL, NULL);
+  if (utf8_name == NULL)
+    utf8_name = g_utf8_make_valid (name, -1);
+
+  case_folded = g_utf8_casefold (utf8_name, -1);
   key = g_utf8_collate_key (case_folded, -1);
 
   found = strcmp (key, e->case_components[depth]) == 0;
 
+  g_free (utf8_name);
   g_free (case_folded);
   g_free (key);
 
diff --git a/gio/tests/contenttype.c b/gio/tests/contenttype.c
index 7fd97f453..8784374f2 100644
--- a/gio/tests/contenttype.c
+++ b/gio/tests/contenttype.c
@@ -360,6 +360,57 @@ test_tree (void)
    }
 }
 
+static void
+test_tree_invalid_encoding (void)
+{
+  gchar *path;
+  gchar *name;
+  GFile *tmpdir;
+  GFile *file;
+  gchar **types;
+  GError *error = NULL;
+
+  g_test_bug ("https://gitlab.gnome.org/GNOME/glib/-/issues/3168");
+
+#if defined(__APPLE__) || defined(G_OS_WIN32)
+  g_test_skip ("The OSX & Windows backends do not implement g_content_type_guess_for_tree()");
+  return;
+#endif
+
+  path = g_dir_make_tmp ("gio-test-tree-invalid-encoding-XXXXXX", &error);
+  g_assert_no_error (error);
+  tmpdir = g_file_new_for_path (path);
+  g_free (path);
+
+  name = g_strdup_printf ("\260");
+  file = g_file_get_child (tmpdir, name);
+  g_free (name);
+
+  g_file_replace_contents (file, "", 0, NULL, FALSE, 0, NULL, NULL, &error);
+  if (g_error_matches (error, G_IO_ERROR, G_IO_ERROR_INVALID_ARGUMENT))
+    {
+      g_test_skip ("Unable to create testing file with non-ASCII characters.");
+
+      g_object_unref (tmpdir);
+      g_object_unref (file);
+      g_clear_error (&error);
+
+      return;
+    }
+  g_assert_no_error (error);
+
+  types = g_content_type_guess_for_tree (tmpdir);
+  g_strfreev (types);
+
+  g_file_delete (file, NULL, &error);
+  g_assert_no_error (error);
+  g_object_unref (file);
+
+  g_file_delete (tmpdir, NULL, &error);
+  g_assert_no_error (error);
+  g_object_unref (tmpdir);
+}
+
 static void
 test_type_is_a_special_case (void)
 {
@@ -442,6 +493,8 @@ main (int argc, char *argv[])
   g_test_add_func ("/contenttype/icon", test_icon);
   g_test_add_func ("/contenttype/symbolic-icon", test_symbolic_icon);
   g_test_add_func ("/contenttype/tree", test_tree);
+  g_test_add_func ("/contenttype/tree_invalid_encoding",
+                   test_tree_invalid_encoding);
   g_test_add_func ("/contenttype/test_type_is_a_special_case",
                    test_type_is_a_special_case);