diff --git a/pySim/ts_102_221.py b/pySim/ts_102_221.py
index ac2a60e..708b50b 100644
--- a/pySim/ts_102_221.py
+++ b/pySim/ts_102_221.py
@@ -186,7 +186,14 @@
 
 # ETSI TS 102 221 11.1.1.4.8
 class ShortFileIdentifier(BER_TLV_IE, tag=0x88):
-    _construct = HexAdapter(COptional(Bytes(1)))
+    # If the length of the TLV is 1, the SFI value is indicated in the 5 most significant bits (bits b8 to b4)
+    # of the TLV value field. In this case, bits b3 to b1 shall be set to 0
+    class Shift3RAdapter(Adapter):
+        def _decode(self, obj, context, path):
+            return obj >> 3
+        def _encode(self, obj, context, path):
+            return obj << 3
+    _construct = COptional(Shift3RAdapter(Byte))
 
 # ETSI TS 102 221 11.1.1.4.9
 class LifeCycleStatusInteger(BER_TLV_IE, tag=0x8A):