diff --git a/spalloc/_keepalive_process.py b/spalloc/_keepalive_process.py
index c358db5d4..49135b0fc 100644
--- a/spalloc/_keepalive_process.py
+++ b/spalloc/_keepalive_process.py
@@ -1,6 +1,7 @@
 """ A script for keeping Spalloc jobs alive, intended to only ever be run\
     from the Spalloc client itself.
 """
+from __future__ import print_function
 import sys
 import threading
 from spalloc.protocol_client import ProtocolClient, ProtocolTimeoutError
@@ -65,6 +66,8 @@ def keep_job_alive(hostname, port, job_id, keepalive_period, timeout,
 
 
 if __name__ == "__main__":
+    print("KEEPALIVE")
+    sys.stdout.flush()
     if len(sys.argv) != 7:
         sys.stderr.write(
             "wrong # args: should be '" + sys.argv[0] + " hostname port "
diff --git a/spalloc/job.py b/spalloc/job.py
index a8b9319c8..33f523ec1 100644
--- a/spalloc/job.py
+++ b/spalloc/job.py
@@ -301,7 +301,16 @@ def __init__(self, *args, **kwargs):
         self._keepalive_process = subprocess.Popen(map(str, [
                 sys.executable, "-m", "spalloc._keepalive_process", hostname,
                 port, self.id, self._keepalive, self._timeout,
-                self._reconnect_delay]), stdin=subprocess.PIPE)
+                self._reconnect_delay]), stdin=subprocess.PIPE,
+                stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
+        first_line = self._keepalive_process.stdout.readline().strip()
+        if first_line.startswith(b"pydev debugger"):
+            first_line = self._keepalive_process.stdout.readline().strip()
+            if len(first_line) == 0:
+                first_line = self._keepalive_process.stdout.readline().strip()
+        if first_line != b"KEEPALIVE":
+            raise Exception("Keepalive process wrote odd line: {}".format(
+                first_line))
 
     def __enter__(self):
         """ Convenience context manager for common case where a new job is to