diff --git a/src/rest.c b/src/rest.c
index 8191648..c0e158e 100644
--- a/src/rest.c
+++ b/src/rest.c
@@ -1355,7 +1355,8 @@ static int og_set_client_mode(struct og_dbi *dbi, const char *mac,
 	dbi_result_next_row(result);
 
 	for (i = 1; i <= dbi_result_get_numfields(result); ++i)
-		strcat(params, dbi_result_get_string_idx(result, i));
+		strncat(params, dbi_result_get_string_idx(result, i),
+		        sizeof(params) - strlen(params) - 1);
 
 	dbi_result_free(result);