diff --git a/libs/subliminal_patch/core.py b/libs/subliminal_patch/core.py
index bcfef632b..a4976efc4 100644
--- a/libs/subliminal_patch/core.py
+++ b/libs/subliminal_patch/core.py
@@ -614,6 +614,10 @@ def _search_external_subtitles(path, languages=None, only_one=False, scandir_gen
         # extract the potential language code
         try:
             language_code = p_root.rsplit(".", 1)[1].replace('_', '-')
+            try:
+                language_code = Language.fromietf(language_code)
+            except ValueError:
+                language_code = None
         except IndexError:
             language_code = None