Replace unprotected tilders by \~ -- an unprotected tilde is a
non-breaking space!
diff --git a/Doc/lib/libtermios.tex b/Doc/lib/libtermios.tex
index ca309c8..1db8af8 100644
--- a/Doc/lib/libtermios.tex
+++ b/Doc/lib/libtermios.tex
@@ -83,7 +83,7 @@
     fd = sys.stdin.fileno()
     old = termios.tcgetattr(fd)
     new = termios.tcgetattr(fd)
-    new[3] = new[3] & ~TERMIOS.ECHO          # lflags
+    new[3] = new[3] & \~TERMIOS.ECHO          # lflags
     try:
         termios.tcsetattr(fd, TERMIOS.TCSADRAIN, new)
         passwd = raw_input(prompt)