diff --git a/src/nxt_conf_validation.c b/src/nxt_conf_validation.c
index 4aaa1b9a8..1beec0139 100644
--- a/src/nxt_conf_validation.c
+++ b/src/nxt_conf_validation.c
@@ -1551,7 +1551,7 @@ static nxt_int_t
 nxt_conf_vldt_var(nxt_conf_validation_t *vldt, const nxt_str_t *name,
     nxt_str_t *value)
 {
-    u_char  error[NXT_MAX_ERROR_STR];
+    u_char  error[NXT_MAX_ERROR_STR] = {0};
 
     if (nxt_tstr_test(vldt->tstr_state, value, error) != NXT_OK) {
         return nxt_conf_vldt_error(vldt, "%s in the \"%V\" value.",