diff --git a/src/stats_statsd.c b/src/stats_statsd.c
index b93d90a..2813410 100644
--- a/src/stats_statsd.c
+++ b/src/stats_statsd.c
@@ -151,7 +151,7 @@
 	const struct osmo_stat_item_group *statg,
 	const struct osmo_stat_item_desc *desc, int value)
 {
-	char *unit = desc->unit;
+	const char *unit = desc->unit;
 
 	if (unit == OSMO_STAT_ITEM_NO_UNIT) {
 		unit = "g";