diff --git a/common/flatpak-utils.c b/common/flatpak-utils.c
index 4d55212e8..042015263 100644
--- a/common/flatpak-utils.c
+++ b/common/flatpak-utils.c
@@ -742,7 +742,6 @@ flatpak_filter_glob_to_regexp (const char  *glob,
   while (*glob != 0)
     {
       char c = *glob;
-      glob++;
 
       if (c == '/')
         {
@@ -774,9 +773,14 @@ flatpak_filter_glob_to_regexp (const char  *glob,
         }
       else
         {
-          flatpak_fail_error (error, FLATPAK_ERROR_INVALID_DATA, _("Invalid glob character '%c'"), c);
+          g_autofree char *first = flatpak_describe_invalid_first_char (glob);
+
+          flatpak_fail_error (error, FLATPAK_ERROR_INVALID_DATA, _("Invalid glob character '%s'"),
+                              first);
           return NULL;
         }
+
+      glob++;
     }
 
   while (parts < 3)
diff --git a/tests/testcommon.c b/tests/testcommon.c
index 89942525c..c3b531b02 100644
--- a/tests/testcommon.c
+++ b/tests/testcommon.c
@@ -834,6 +834,14 @@ test_filter_parser (void)
      "deny *\n"
      "allow org.foo.bar extra\n",
      FLATPAK_ERROR_INVALID_DATA
+    },
+    {
+     "deny \xf0\x9f\x98\xb9",
+     FLATPAK_ERROR_INVALID_DATA
+    },
+    {
+     "deny \xff",
+     FLATPAK_ERROR_INVALID_DATA
     }
   };
   gboolean ret;
@@ -841,12 +849,15 @@ test_filter_parser (void)
 
   for (i = 0; i < G_N_ELEMENTS(filters); i++)
     {
+      g_autofree char *escaped = flatpak_escape_string (filters[i].filter, FLATPAK_ESCAPE_DO_NOT_QUOTE);
       g_autoptr(GError) error = NULL;
       g_autoptr(GRegex) allow_refs = NULL;
       g_autoptr(GRegex) deny_refs = NULL;
 
       ret = flatpak_parse_filters (filters[i].filter, &allow_refs, &deny_refs, &error);
       g_assert_error (error, FLATPAK_ERROR, filters[i].expected_error);
+      g_test_message ("Invalid filter \"%s\" -> %s", escaped, error->message);
+      g_assert_true (g_utf8_validate (error->message, -1, NULL));
       g_assert_true (ret == FALSE);
       g_assert_true (allow_refs == NULL);
       g_assert_true (deny_refs == NULL);