--- gforth/engine/io.c	2008/11/01 22:19:30	1.34
+++ gforth/engine/io.c	2009/06/13 10:22:24	1.35
@@ -622,6 +622,7 @@ long key_avail (FILE * stream)
   int tty = fileno (stream);
   fd_set selin;
   static struct timeval now = { 0 , 0 };
+  int chars_avail;
 
   setvbuf(stream, NULL, _IONBF, 0);
   if(!terminal_prepped && stream == stdin)
@@ -629,7 +630,8 @@ long key_avail (FILE * stream)
 
   FD_ZERO(&selin);
   FD_SET(tty, &selin);
-  return select(1, &selin, NULL, NULL, &now);
+  chars_avail = select(1, &selin, NULL, NULL, &now);
+  return (chars_avail == -1) ? 0 : chars_avail;
 }
 
 /* Get a key from the buffer of characters to be read.