diff --git a/src/bin/pg_basebackup/bbstreamer_lz4.c b/src/bin/pg_basebackup/bbstreamer_lz4.c
index 395fcb92795..782f5581559 100644
--- a/src/bin/pg_basebackup/bbstreamer_lz4.c
+++ b/src/bin/pg_basebackup/bbstreamer_lz4.c
@@ -320,9 +320,9 @@ bbstreamer_lz4_decompressor_content(bbstreamer *streamer,
 
 	mystreamer = (bbstreamer_lz4_frame *) streamer;
 	next_in = (uint8 *) data;
-	next_out = (uint8 *) mystreamer->base.bbs_buffer.data;
+	next_out = (uint8 *) mystreamer->base.bbs_buffer.data + mystreamer->bytes_written;
 	avail_in = len;
-	avail_out = mystreamer->base.bbs_buffer.maxlen;
+	avail_out = mystreamer->base.bbs_buffer.maxlen - mystreamer->bytes_written;
 
 	while (avail_in > 0)
 	{
diff --git a/src/bin/pg_verifybackup/t/008_untar.pl b/src/bin/pg_verifybackup/t/008_untar.pl
index 1a783d11883..5bd2e303d2a 100644
--- a/src/bin/pg_verifybackup/t/008_untar.pl
+++ b/src/bin/pg_verifybackup/t/008_untar.pl
@@ -16,6 +16,22 @@ my $primary = PostgreSQL::Test::Cluster->new('primary');
 $primary->init(allows_streaming => 1);
 $primary->start;
 
+# Create file with some random data and an arbitrary size, useful to check
+# the solidity of the compression and decompression logic.  The size of the
+# file is chosen to be around 640kB.  This has proven to be large enough to
+# detect some issues related to LZ4, and low enough to not impact the runtime
+# of the test significantly.
+my $junk_data = $primary->safe_psql(
+	'postgres', qq(
+		SELECT string_agg(encode(sha256(i::text::bytea), 'hex'), '')
+		FROM generate_series(1, 10240) s(i);));
+my $data_dir = $primary->data_dir;
+my $junk_file = "$data_dir/junk";
+open my $jf, '>', $junk_file
+  or die "Could not create junk file: $!";
+print $jf $junk_data;
+close $jf;
+
 my $backup_path = $primary->backup_dir . '/server-backup';
 my $extract_path = $primary->backup_dir . '/extracted-backup';
 
@@ -42,6 +58,14 @@ my @test_configuration = (
 		'decompress_flags' => [ '-d', '-m' ],
 		'enabled' => check_pg_config("#define USE_LZ4 1")
 	},
+	{
+		'compression_method' => 'lz4',
+		'backup_flags' => [ '--compress', 'server-lz4:5' ],
+		'backup_archive' => 'base.tar.lz4',
+		'decompress_program' => $ENV{'LZ4'},
+		'decompress_flags' => [ '-d', '-m' ],
+		'enabled' => check_pg_config("#define USE_LZ4 1")
+	},
 	{
 		'compression_method' => 'zstd',
 		'backup_flags' => [ '--compress', 'server-zstd' ],
diff --git a/src/bin/pg_verifybackup/t/010_client_untar.pl b/src/bin/pg_verifybackup/t/010_client_untar.pl
index 44d83e777ff..6050da2bf9d 100644
--- a/src/bin/pg_verifybackup/t/010_client_untar.pl
+++ b/src/bin/pg_verifybackup/t/010_client_untar.pl
@@ -15,6 +15,22 @@ my $primary = PostgreSQL::Test::Cluster->new('primary');
 $primary->init(allows_streaming => 1);
 $primary->start;
 
+# Create file with some random data and an arbitrary size, useful to check
+# the solidity of the compression and decompression logic.  The size of the
+# file is chosen to be around 640kB.  This has proven to be large enough to
+# detect some issues related to LZ4, and low enough to not impact the runtime
+# of the test significantly.
+my $junk_data = $primary->safe_psql(
+	'postgres', qq(
+		SELECT string_agg(encode(sha256(i::text::bytea), 'hex'), '')
+		FROM generate_series(1, 10240) s(i);));
+my $data_dir = $primary->data_dir;
+my $junk_file = "$data_dir/junk";
+open my $jf, '>', $junk_file
+  or die "Could not create junk file: $!";
+print $jf $junk_data;
+close $jf;
+
 my $backup_path = $primary->backup_dir . '/client-backup';
 my $extract_path = $primary->backup_dir . '/extracted-backup';
 
@@ -42,6 +58,15 @@ my @test_configuration = (
 		'output_file' => 'base.tar',
 		'enabled' => check_pg_config("#define USE_LZ4 1")
 	},
+	{
+		'compression_method' => 'lz4',
+		'backup_flags' => [ '--compress', 'client-lz4:1' ],
+		'backup_archive' => 'base.tar.lz4',
+		'decompress_program' => $ENV{'LZ4'},
+		'decompress_flags' => ['-d'],
+		'output_file' => 'base.tar',
+		'enabled' => check_pg_config("#define USE_LZ4 1")
+	},
 	{
 		'compression_method' => 'zstd',
 		'backup_flags' => [ '--compress', 'client-zstd:5' ],