diff --git a/src/viewer/dump/dump.c b/src/viewer/dump/dump.c
index 379e324b..9317b13b 100644
--- a/src/viewer/dump/dump.c
+++ b/src/viewer/dump/dump.c
@@ -565,7 +565,7 @@ subst_url(char *str, struct string *url)
 }
 
 static void
-dump_print(char *option, struct string *url)
+dump_print(const char *option, struct string *url)
 {
 	char *str = get_opt_str(option, NULL);