diff --git a/escpos/escpos.py b/escpos/escpos.py
index f18b169..62c90b1 100644
--- a/escpos/escpos.py
+++ b/escpos/escpos.py
@@ -421,7 +421,7 @@ class Escpos(object):
         else:  # DEFAULT POSITION: BELOW
             self._raw(BARCODE_TXT_BLW)
 
-        bc_types = BARCODE_TYPES[function_type]
+        bc_types = BARCODE_TYPES[function_type.upper()]
         if bc.upper() not in bc_types.keys():
             # TODO: Raise a better error, or fix the message of this error type
             raise BarcodeTypeError("Barcode type {bc} not valid for barcode function type {function_type}".format(