diff --git a/src/proto/os_win32.pro b/src/proto/os_win32.pro
index dd2c27e..6633560 100644
--- a/src/proto/os_win32.pro
+++ b/src/proto/os_win32.pro
@@ -85,5 +85,5 @@
 void resize_console_buf(void);
 char *GetWin32Error(void);
 void stop_timeout(void);
-volatile int *start_timeout(long msec);
+volatile sig_atomic_t *start_timeout(long msec);
 /* vim: set ft=c : */