diff --git a/src/dir.c b/src/dir.c
index 2f6d8090..8732e712 100644
--- a/src/dir.c
+++ b/src/dir.c
@@ -187,7 +187,7 @@ pgFile *
 pgFileInit(const char *path, const char *rel_path)
 {
 	pgFile	   *file;
-	char	   *file_name;
+	char	   *file_name = NULL;
 
 	file = (pgFile *) pgut_malloc(sizeof(pgFile));
 	MemSet(file, 0, sizeof(pgFile));
@@ -414,6 +414,16 @@ pgFileComparePathWithExternalDesc(const void *f1, const void *f2)
 	return -pgFileComparePathWithExternal(f1, f2);
 }
 
+/*
+ * Compare two pgFile with their rel_path and external_dir_num
+ * in descending order of ASCII code.
+ */
+int
+pgFileCompareRelPathWithExternalDesc(const void *f1, const void *f2)
+{
+	return -pgFileCompareRelPathWithExternal(f1, f2);
+}
+
 /* Compare two pgFile with their linked directory path. */
 int
 pgFileCompareLinked(const void *f1, const void *f2)
diff --git a/src/merge.c b/src/merge.c
index e3358bd9..2d00fa78 100644
--- a/src/merge.c
+++ b/src/merge.c
@@ -236,7 +236,7 @@ merge_backups(pgBackup *to_backup, pgBackup *from_backup)
 					DATABASE_FILE_LIST);
 	to_files = dir_read_file_list(NULL, NULL, control_file, FIO_BACKUP_HOST);
 	/* To delete from leaf, sort in reversed order */
-	parray_qsort(to_files, pgFileComparePathWithExternalDesc);
+	parray_qsort(to_files, pgFileCompareRelPathWithExternalDesc);
 	/*
 	 * Get list of files which need to be moved.
 	 */
@@ -385,7 +385,7 @@ delete_source_backup:
 	/*
 	 * Delete files which are not in from_backup file list.
 	 */
-	parray_qsort(files, pgFileComparePathWithExternalDesc);
+	parray_qsort(files, pgFileCompareRelPathWithExternalDesc);
 	for (i = 0; i < parray_num(to_files); i++)
 	{
 		pgFile	   *file = (pgFile *) parray_get(to_files, i);
@@ -398,7 +398,7 @@ delete_source_backup:
 				continue;
 		}
 
-		if (parray_bsearch(files, file, pgFileComparePathWithExternalDesc) == NULL)
+		if (parray_bsearch(files, file, pgFileCompareRelPathWithExternalDesc) == NULL)
 		{
 			char		to_file_path[MAXPGPATH];
 			char	   *prev_path;
@@ -488,7 +488,7 @@ merge_files(void *arg)
 				 i + 1, num_files, file->path);
 
 		res_file = parray_bsearch(argument->to_files, file,
-								  pgFileComparePathWithExternalDesc);
+								  pgFileCompareRelPathWithExternalDesc);
 		to_file = (res_file) ? *res_file : NULL;
 
 		join_path_components(to_file_path, argument->to_root, file->path);
diff --git a/src/pg_probackup.h b/src/pg_probackup.h
index 40b8ccb0..690e4d33 100644
--- a/src/pg_probackup.h
+++ b/src/pg_probackup.h
@@ -668,6 +668,7 @@ extern int pgFileCompareName(const void *f1, const void *f2);
 extern int pgFileComparePath(const void *f1, const void *f2);
 extern int pgFileComparePathWithExternal(const void *f1, const void *f2);
 extern int pgFileCompareRelPathWithExternal(const void *f1, const void *f2);
+extern int pgFileCompareRelPathWithExternalDesc(const void *f1, const void *f2);
 extern int pgFileComparePathDesc(const void *f1, const void *f2);
 extern int pgFileComparePathWithExternalDesc(const void *f1, const void *f2);
 extern int pgFileCompareLinked(const void *f1, const void *f2);