diff --git a/src/http/modules/ngx_http_memcached_module.c b/src/http/modules/ngx_http_memcached_module.c
index bda038d..9636028 100644
--- a/src/http/modules/ngx_http_memcached_module.c
+++ b/src/http/modules/ngx_http_memcached_module.c
@@ -391,7 +391,7 @@
         p = line.data + line.len;
 
         u->headers_in.content_length_n = ngx_atoof(start, p - start);
-        if (u->headers_in.content_length_n == -1) {
+        if (u->headers_in.content_length_n == NGX_ERROR) {
             ngx_log_error(NGX_LOG_ERR, r->connection->log, 0,
                           "memcached sent invalid length in response \"%V\" "
                           "for key \"%V\"",