diff --git a/pySim/utils.py b/pySim/utils.py
index b49a437f..d75a000c 100644
--- a/pySim/utils.py
+++ b/pySim/utils.py
@@ -109,8 +109,8 @@ def enc_iccid(iccid):
 def enc_plmn(mcc, mnc):
 	"""Converts integer MCC/MNC into 3 bytes for EF"""
 	if len(mnc) == 2:
-		mnc = "F%s" % mnc
-	return swap_nibbles("%s%s" % (mcc, mnc))
+		mnc += "F" # pad to 3 digits if needed
+	return (mcc[1] + mcc[0]) + (mnc[2] + mcc[2]) + (mnc[1] + mnc[0])
 
 def dec_spn(ef):
 	byte1 = int(ef[0:2])
diff --git a/tests/test_utils.py b/tests/test_utils.py
index 44fe631a..0df205ae 100644
--- a/tests/test_utils.py
+++ b/tests/test_utils.py
@@ -29,6 +29,16 @@ class DecTestCase(unittest.TestCase):
 	def testDecMNCfromPLMN_unused(self):
 		self.assertEqual(utils.dec_mnc_from_plmn("00f0ff"), 4095)
 
+	def test_enc_plmn(self):
+		with self.subTest("2-digit MCC"):
+			self.assertEqual(utils.enc_plmn("001", "01F"), "00F110")
+			self.assertEqual(utils.enc_plmn("001", "01"), "00F110")
+			self.assertEqual(utils.enc_plmn("295", "10"), "92F501")
+
+		with self.subTest("3-digit MCC"):
+			self.assertEqual(utils.enc_plmn("001", "001"), "001100")
+			self.assertEqual(utils.enc_plmn("302", "361"), "031263")
+
 	def testDecAct_noneSet(self):
 		self.assertEqual(utils.dec_act("0000"), [])