Index: src/shell.c
==================================================================
--- src/shell.c
+++ src/shell.c
@@ -69,11 +69,11 @@
 #define isatty(h) _isatty(h)
 #define access(f,m) _access((f),(m))
 #else
 /* Make sure isatty() has a prototype.
 */
-extern int isatty();
+extern int isatty(int);
 #endif
 
 #if defined(_WIN32_WCE)
 /* Windows CE (arm-wince-mingw32ce-gcc) does not provide isatty()
  * thus we always assume that we have a console. That can be