diff --git a/redo/builder.py b/redo/builder.py.new
index e55955f7f9..160cba8dfe 100644
--- a/redo/builder.py
+++ b/redo/builder.py.new
@@ -1,5 +1,5 @@
 """Code for parallel-building a set of targets, if needed."""
-import errno, os, stat, signal, sys, tempfile, time
+import errno, os, os.path, stat, signal, sys, tempfile, time
 from . import cycles, env, jobserver, logs, state, paths
 from .helpers import unlink, close_on_exec
 from .logs import debug2, err, warn, meta
@@ -99,6 +99,8 @@ def await_log_reader():
     if not env.v.LOG:
         return
     if log_reader_pid > 0:
+        if not os.path.exists('/dev/tty'):
+            return
         # never actually close fd#1 or fd#2; insanity awaits.
         # replace it with something else instead.
         # Since our stdout/stderr are attached to redo-log's stdin,