diff --git a/lib/roken/strptime.c b/lib/roken/strptime.c
index c4e4e0a31..e60d94ec8 100644
--- a/lib/roken/strptime.c
+++ b/lib/roken/strptime.c
@@ -436,5 +436,5 @@ strptime (const char *buf, const char *format, struct tm *timeptr)
 		return NULL;
 	}
     }
-    return (char *)buf;
+    return rk_UNCONST(buf);
 }