diff --git a/src/os/win32/ngx_wsasend_chain.c b/src/os/win32/ngx_wsasend_chain.c
index e28e1ee31..fa725248c 100644
--- a/src/os/win32/ngx_wsasend_chain.c
+++ b/src/os/win32/ngx_wsasend_chain.c
@@ -34,7 +34,7 @@ ngx_wsasend_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
 
     /* the maximum limit size is the maximum u_long value - the page size */
 
-    if (limit == 0 || limit > NGX_MAX_UINT32_VALUE - ngx_pagesize) {
+    if (limit == 0 || limit > (off_t) (NGX_MAX_UINT32_VALUE - ngx_pagesize)) {
         limit = NGX_MAX_UINT32_VALUE - ngx_pagesize;
     }
 
@@ -156,7 +156,7 @@ ngx_overlapped_wsasend_chain(ngx_connection_t *c, ngx_chain_t *in, off_t limit)
 
         /* the maximum limit size is the maximum u_long value - the page size */
 
-        if (limit == 0 || limit > NGX_MAX_UINT32_VALUE - ngx_pagesize) {
+        if (limit == 0 || limit > (off_t) (NGX_MAX_UINT32_VALUE - ngx_pagesize)) {
             limit = NGX_MAX_UINT32_VALUE - ngx_pagesize;
         }