diff --git a/stat.c b/stat.c
index 0ae19b2..0ccf37e 100644
--- a/stat.c
+++ b/stat.c
@@ -333,7 +333,7 @@
 static void show_ddir_status(struct thread_data *td, struct group_run_stats *rs,
 			     int ddir)
 {
-	char *ddir_str[] = { "read ", "write" };
+	const char *ddir_str[] = { "read ", "write" };
 	unsigned long min, max;
 	unsigned long long bw;
 	double mean, dev;