diff --git a/python_gpt_po/po_translator.py b/python_gpt_po/po_translator.py
index e090c96..2d4e312 100644
--- a/python_gpt_po/po_translator.py
+++ b/python_gpt_po/po_translator.py
@@ -10,6 +10,7 @@
 from dataclasses import dataclass
 
 import polib
+import pycountry
 from dotenv import load_dotenv
 from openai import OpenAI
 from pkg_resources import DistributionNotFound, get_distribution
@@ -58,18 +59,43 @@ def disable_fuzzy_translations(po_file_path):
     @staticmethod
     def get_file_language(po_file_path, po_file, languages, folder_language):
         """Determines the language for a .po file."""
-        # Attempt to get language from the file metadata first
         file_lang = po_file.metadata.get('Language', '')
+        normalized_lang = POFileHandler.normalize_language_code(file_lang)
 
-        # If the file's language is not valid, infer it from the folder structure
-        if not file_lang or file_lang not in languages:
-            if folder_language:
-                inferred_lang = next((part for part in po_file_path.split(os.sep) if part in languages), None)
-                if inferred_lang:
-                    logging.info("Inferred language for .po file: %s as %s", po_file_path, inferred_lang)
-                    return inferred_lang
-            return None
-        return file_lang
+        if normalized_lang in languages:
+            return normalized_lang
+
+        if folder_language:
+            for part in po_file_path.split(os.sep):
+                norm_part = POFileHandler.normalize_language_code(part)
+                if norm_part in languages:
+                    logging.info("Inferred language for .po file: %s as %s", po_file_path, norm_part)
+                    return norm_part
+
+        return None
+
+    @staticmethod
+    def normalize_language_code(lang):
+        """Convert language name or code to ISO 639-1 code."""
+        # Try direct lookup
+        if len(lang) == 2:
+            try:
+                return pycountry.languages.get(alpha_2=lang.lower()).alpha_2
+            except AttributeError:
+                pass
+
+        # Try by name
+        try:
+            return pycountry.languages.get(name=lang.title()).alpha_2
+        except AttributeError:
+            pass
+
+        # Try by native name
+        for language in pycountry.languages:
+            if hasattr(language, 'inverted_name') and language.inverted_name.lower() == lang.lower():
+                return language.alpha_2
+
+        return None
 
     @staticmethod
     def log_translation_status(po_file_path, original_texts, translations):
diff --git a/requirements.txt b/requirements.txt
index 59408a2..8c9fa1c 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -1,6 +1,7 @@
 polib==1.2.0
-openai==v1.42.0
+openai==1.58.1
 python-dotenv==1.0.0
 pytest==8.2.2
 tenacity==9.0.0
-setuptools-scm==8.1.0
\ No newline at end of file
+setuptools-scm==8.1.0
+pycountry==24.6.1
\ No newline at end of file
diff --git a/setup.py b/setup.py
index 6956bb3..551997a 100644
--- a/setup.py
+++ b/setup.py
@@ -24,7 +24,7 @@
     include_package_data=True,
     install_requires=[
         'polib==1.2.0',
-        'openai==v1.42.0',
+        'openai==1.58.1',
         'python-dotenv==1.0.0',
         'tenacity==9.0.0',
     ],