diff --git a/src/bin/pg_basebackup/pg_basebackup.c b/src/bin/pg_basebackup/pg_basebackup.c
index 613f2e159c..c4455c8389 100644
--- a/src/bin/pg_basebackup/pg_basebackup.c
+++ b/src/bin/pg_basebackup/pg_basebackup.c
@@ -201,6 +201,11 @@ tablespace_list_append(const char *arg)
 		exit(1);
 	}
 
+	/*
+	 * Comparisons done with those values should involve similarly
+	 * canonicalized path values. This is particularly sensitive on
+	 * Windows where path values may not necessarily use Unix slashes.
+	 */
 	canonicalize_path(cell->old_dir);
 	canonicalize_path(cell->new_dir);
 
@@ -1127,6 +1132,11 @@ static const char *
 get_tablespace_mapping(const char *dir)
 {
 	TablespaceListCell *cell;
+	char				canon_dir[MAXPGPATH];
+
+	/* Canonicalize path for comparison consistency */
+	strcpy(canon_dir, dir);
+	canonicalize_path(canon_dir);
 
 	for (cell = tablespace_dirs.head; cell; cell = cell->next)
 		if (strcmp(dir, cell->old_dir) == 0)