diff --git a/delete.c b/delete.c
index 284ed800..4c410eee 100644
--- a/delete.c
+++ b/delete.c
@@ -349,12 +349,10 @@ delete_walfiles(XLogRecPtr oldest_lsn, TimeLineID oldest_tli, bool delete_all)
 			 * they were originally written, in case this worries you.
 			 */
 			if (IsXLogFileName(arcde->d_name) ||
-				IsPartialXLogFileName(arcde->d_name) ||
-				IsBackupHistoryFileName(arcde->d_name))
+				IsPartialXLogFileName(arcde->d_name))
 			{
 				if (XLogRecPtrIsInvalid(oldest_lsn) ||
-					strncmp(arcde->d_name, oldestSegmentNeeded,
-							XLOG_FNAME_LEN) < 0)
+					strcmp(arcde->d_name + 8, oldestSegmentNeeded + 8) < 0)
 				{
 					/*
 					 * Use the original file name again now, including any
diff --git a/tests/option_test.py b/tests/option_test.py
index c973bfaa..ee52343e 100644
--- a/tests/option_test.py
+++ b/tests/option_test.py
@@ -89,7 +89,21 @@ class OptionTest(ProbackupTest, unittest.TestCase):
 		self.clean_pb(node)
 		self.assertEqual(self.init_pb(node), six.b(""))
 
-		# TODO: keep data generations
+		# Command line parameters should override file values
+		self.init_pb(node)
+		with open(path.join(self.backup_dir(node), "pg_probackup.conf"), "a") as conf:
+			conf.write("REDUNDANCY=1\n")
+
+		self.assertEqual(
+			self.retention_show(node, ["--redundancy", "2"]),
+			six.b("# retention policy\nREDUNDANCY=2\n")
+		)
+
+		# User cannot send --system-identifier parameter via command line
+		self.assertEqual(
+			self.backup_pb(node, options=["--system-identifier", "123"]),
+			six.b("ERROR: option system-identifier cannot be specified in command line\n")
+		)
 
 		# invalid value in pg_probackup.conf
 		with open(path.join(self.backup_dir(node), "pg_probackup.conf"), "a") as conf:
diff --git a/tests/pb_lib.py b/tests/pb_lib.py
index 32a1e174..393aa6e7 100644
--- a/tests/pb_lib.py
+++ b/tests/pb_lib.py
@@ -195,6 +195,14 @@ class ProbackupTest(object):
 
 		return self.run_pb(options + cmd_list)
 
+	def retention_show(self, node, options=[]):
+		cmd_list = [
+			"-B", self.backup_dir(node),
+			"retention", "show",
+		]
+
+		return self.run_pb(options + cmd_list)
+
 	def get_control_data(self, node):
 		pg_controldata = node.get_bin_path("pg_controldata")
 		out_data = {}
diff --git a/tests/retention_test.py b/tests/retention_test.py
index 5712eeaf..5a4ef3a3 100644
--- a/tests/retention_test.py
+++ b/tests/retention_test.py
@@ -1,7 +1,7 @@
 import unittest
 import os
 from datetime import datetime, timedelta
-from os import path
+from os import path, listdir
 from .pb_lib import ProbackupTest
 from testgres import stop_all
 
@@ -35,9 +35,23 @@ class RetentionTest(ProbackupTest, unittest.TestCase):
 		self.assertEqual(len(self.show_pb(node)), 4)
 
 		# Purge backups
-		self.retention_purge_pb(node)
+		log = self.retention_purge_pb(node)
 		self.assertEqual(len(self.show_pb(node)), 2)
 
+		# Check that WAL segments were deleted
+		min_wal = None
+		max_wal = None
+		for line in log.splitlines():
+			if line.startswith(b"INFO: removed min WAL segment"):
+				min_wal = line[31:-1]
+			elif line.startswith(b"INFO: removed max WAL segment"):
+				max_wal = line[31:-1]
+		for wal_name in listdir(path.join(self.backup_dir(node), "wal")):
+			if not wal_name.endswith(".backup"):
+				wal_name_b = wal_name.encode('ascii')
+				self.assertEqual(wal_name_b[8:] > min_wal[8:], True)
+				self.assertEqual(wal_name_b[8:] > max_wal[8:], True)
+
 		node.stop()
 
 	def test_retention_window_2(self):