diff --git a/src/posixos.c b/src/posixos.c
index 66f6e49c..39b4a3ec 100644
--- a/src/posixos.c
+++ b/src/posixos.c
@@ -116,6 +116,9 @@ make_job_rfd ()
   EINTRLOOP (job_rfd, dup (job_fds[0]));
   if (job_rfd >= 0)
     fd_noinherit (job_rfd);
+  else
+    ONS (error, NILF,
+         "cannot dup jobserver FD %d: %s", job_fds[0], strerror (errno));
 
   return job_rfd;
 #endif
@@ -256,11 +259,18 @@ jobserver_parse_auth (const char *auth)
     {
       /* The parent overrode our FDs because we aren't a recursive make.  */
       if (rfd == -2 || wfd == -2)
-        return 0;
+        {
+          ONN (error, NILF, "not recursive %d,%d", rfd, wfd);
+          return 0;
+        }
 
       /* Make sure our pipeline is valid.  */
       if (!FD_OK (rfd) || !FD_OK (wfd))
-        return 0;
+        {
+          error (NILF, strlen (strerror (errno)) + INTSTR_LENGTH*2,
+                 "not OK %d,%d: %s", rfd, wfd, strerror (errno));
+          return 0;
+        }
 
       job_fds[0] = rfd;
       job_fds[1] = wfd;