diff --git a/src/core/ngx_cycle.c b/src/core/ngx_cycle.c
index bde3171ae..24e30f7b1 100644
--- a/src/core/ngx_cycle.c
+++ b/src/core/ngx_cycle.c
@@ -469,7 +469,7 @@ ngx_int_t ngx_create_pidfile(ngx_cycle_t *cycle, ngx_cycle_t *old_cycle)
     file.log = cycle->log;
 
     file.fd = ngx_open_file(file.name.data, NGX_FILE_RDWR,
-                            NGX_FILE_CREATE_OR_OPEN);
+                            NGX_FILE_CREATE_OR_OPEN|NGX_FILE_TRUNCATE);
 
     if (file.fd == NGX_INVALID_FILE) {
         ngx_log_error(NGX_LOG_EMERG, cycle->log, ngx_errno,
diff --git a/src/http/ngx_http_write_filter.c b/src/http/ngx_http_write_filter.c
index 05675374d..1728c6459 100644
--- a/src/http/ngx_http_write_filter.c
+++ b/src/http/ngx_http_write_filter.c
@@ -143,8 +143,10 @@ int ngx_http_write_filter(ngx_http_request_t *r, ngx_chain_t *in)
     }
 
     if (size == 0) {
-        ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
-                      "the http output chain is empty");
+        if (!last) {
+            ngx_log_error(NGX_LOG_ALERT, r->connection->log, 0,
+                          "the http output chain is empty");
+        }
         return NGX_OK;
     }
 
diff --git a/src/os/unix/ngx_files.h b/src/os/unix/ngx_files.h
index afc5367a3..9fe837092 100644
--- a/src/os/unix/ngx_files.h
+++ b/src/os/unix/ngx_files.h
@@ -19,6 +19,7 @@
 #define NGX_FILE_RDWR            O_RDWR
 #define NGX_FILE_CREATE_OR_OPEN  O_CREAT
 #define NGX_FILE_OPEN            0
+#define NGX_FILE_TRUNCATE        O_TRUNC
 #define NGX_FILE_APPEND          O_APPEND