diff --git a/Documentation/redo.md b/Documentation/redo.md
index b98d189..4a4024a 100644
--- a/Documentation/redo.md
+++ b/Documentation/redo.md
@@ -38,6 +38,11 @@ instead.
 A .do script can call redo recursively to build its
 dependencies.
 
+To avoid confusion caused by multiple programs trying to
+use the terminal, inside .do scripts, stdin is normally
+redirected to /dev/null.  The only exception is if the `-j`
+option is *not* given and `--no-log` is used.
+
 
 # OPTIONS
 
diff --git a/builder.py b/builder.py
index 5c4bd69..3f5d422 100644
--- a/builder.py
+++ b/builder.py
@@ -22,9 +22,14 @@ def _try_stat(filename):
 log_reader_pid = None
 
 
+def close_stdin():
+    f = open('/dev/null')
+    os.dup2(f.fileno(), 0)
+    f.close()
+
+
 def start_stdin_log_reader(status, details, pretty, color,
                            debug_locks, debug_pids):
-    if not vars.LOG: return
     global log_reader_pid
     r, w = os.pipe()    # main pipe to redo-log
     ar, aw = os.pipe()  # ack pipe from redo-log --ack-fd
diff --git a/redo-ifchange.py b/redo-ifchange.py
index d4d7cb7..c9db239 100755
--- a/redo-ifchange.py
+++ b/redo-ifchange.py
@@ -19,7 +19,8 @@ def should_build(t):
 
 rv = 202
 try:
-    if vars_init.is_toplevel:
+    if vars_init.is_toplevel and vars.LOG:
+        builder.close_stdin()
         builder.start_stdin_log_reader(status=True, details=True,
             pretty=True, color=True, debug_locks=False, debug_pids=False)
     if vars.TARGET and not vars.UNLOCKED:
diff --git a/redo.py b/redo.py
index 80c0224..4303df2 100755
--- a/redo.py
+++ b/redo.py
@@ -79,7 +79,10 @@ import vars, state, builder, jwack
 from logs import warn, err
 
 try:
-    if vars_init.is_toplevel:
+    j = atoi(opt.jobs or 1)
+    if vars_init.is_toplevel and (vars.LOG or j > 1):
+        builder.close_stdin()
+    if vars_init.is_toplevel and vars.LOG:
         builder.start_stdin_log_reader(status=opt.status, details=opt.details,
             pretty=opt.pretty, color=opt.color,
             debug_locks=opt.debug_locks, debug_pids=opt.debug_pids)
@@ -91,7 +94,6 @@ try:
                      % f.nicename())
     state.rollback()
     
-    j = atoi(opt.jobs or 1)
     if j < 1 or j > 1000:
         err('invalid --jobs value: %r\n' % opt.jobs)
     jwack.setup(j)