diff --git a/ox/iso.py b/ox/iso.py
index 3b92acb..6c28435 100644
--- a/ox/iso.py
+++ b/ox/iso.py
@@ -192,33 +192,36 @@ _iso639_languages = [
 ]
 
 def codeToLang(code):
-    code = code.lower()
-    if len(code) == 2:
-        for l in _iso639_languages:
-            if l[2] == code:
-                return l[0]
-    elif len(code) == 3:
-        for l in _iso639_languages:
-            if l[3] == code:
-                return l[0]
+    if code:
+        code = code.lower()
+        if len(code) == 2:
+            for l in _iso639_languages:
+                if l[2] == code:
+                    return l[0]
+        elif len(code) == 3:
+            for l in _iso639_languages:
+                if l[3] == code:
+                    return l[0]
     return None
 
 def langTo3Code(lang):
-    lang = langEnglishName(lang)
     if lang:
-        lang=lang.lower()
-    for l in _iso639_languages:
-        if l[0].lower() == lang:
-            return l[3]
+        lang = langEnglishName(lang)
+        if lang:
+            lang=lang.lower()
+        for l in _iso639_languages:
+            if l[0].lower() == lang:
+                return l[3]
     return None
 
 def langTo2Code(lang):
-    lang = langEnglishName(lang)
     if lang:
-        lang=lang.lower()
-    for l in _iso639_languages:
-        if l[0].lower() == lang:
-            return l[2]
+        lang = langEnglishName(lang)
+        if lang:
+            lang=lang.lower()
+        for l in _iso639_languages:
+            if l[0].lower() == lang:
+                return l[2]
     return None
 
 def langCode2To3(code):
@@ -230,7 +233,7 @@ def langCode3To2(code):
 def langEnglishName(lang):
     lang = lang.lower()
     for l in _iso639_languages:
-        if l[1].lower() == lang:
+        if l[1].lower() == lang or l[0].lower() == lang:
             return l[0]
     return None