NGX_HTTP_PRECONDITION_FAILED
diff --git a/src/http/ngx_http_request.h b/src/http/ngx_http_request.h
index 5cdcb94..22e17ee 100644
--- a/src/http/ngx_http_request.h
+++ b/src/http/ngx_http_request.h
@@ -77,6 +77,7 @@
 #define NGX_HTTP_REQUEST_TIME_OUT          408
 #define NGX_HTTP_CONFLICT                  409
 #define NGX_HTTP_LENGTH_REQUIRED           411
+#define NGX_HTTP_PRECONDITION_FAILED       412
 #define NGX_HTTP_REQUEST_ENTITY_TOO_LARGE  413
 #define NGX_HTTP_REQUEST_URI_TOO_LARGE     414
 #define NGX_HTTP_UNSUPPORTED_MEDIA_TYPE    415