diff --git a/libfcgi/os_win32.c b/libfcgi/os_win32.c
index 1a77ca6..27d8fcc 100755
--- a/libfcgi/os_win32.c
+++ b/libfcgi/os_win32.c
@@ -1546,7 +1546,7 @@ static int CALLBACK isAddrOKCallback(LPWSABUF  lpCallerId,
                                      LPWSABUF  dc3,
                                      LPWSABUF  dc4,
                                      GROUP     *dc5,
-                                     DWORD     data)
+                                     DWORD_PTR data)
 {
     struct sockaddr_in *sockaddr = (struct sockaddr_in *) lpCallerId->buf;
 
@@ -1678,7 +1678,7 @@ static int acceptSocket(const char *webServerAddrs)
                           &sockaddr,  
                           &sockaddrLen,               
                           isAddrOKCallback,  
-                          (DWORD) webServerAddrs);
+                          (DWORD_PTR) webServerAddrs);
 
         if (hSock != INVALID_SOCKET)
         {