diff --git a/C/iopreds.c b/C/iopreds.c
index 40bb68b17..3f4019112 100644
--- a/C/iopreds.c
+++ b/C/iopreds.c
@@ -1426,8 +1426,10 @@ InitSocketStream(int fd, socket_info flags, socket_domain domain) {
   for (sno = 0; sno < MaxStreams; ++sno)
     if (Stream[sno].status & Free_Stream_f)
       break;
-  if (sno == MaxStreams)
-    return (PlIOError (SYSTEM_ERROR,TermNil, "new stream not available for socket/4"));
+  if (sno == MaxStreams) {
+    PlIOError (SYSTEM_ERROR,TermNil, "new stream not available for socket/4");
+    return(TermNil);
+  }
   st = &Stream[sno];
   st->u.socket.domain = domain;
   st->u.socket.flags = flags;
diff --git a/C/ypsocks.c b/C/ypsocks.c
index 6211cc8ce..a534e61f8 100644
--- a/C/ypsocks.c
+++ b/C/ypsocks.c
@@ -454,6 +454,7 @@ p_socket(void)
 #endif
     return(FALSE);
   }
+  if (out == TermNil) return(FALSE);
   return(unify(out,ARG4));
 }
 
@@ -897,6 +898,7 @@ p_socket_accept(void)
     out = InitSocketStream(fd, server_session_socket, af_inet );
   } else
       return(FALSE);
+  if (out == TermNil) return(FALSE);
   return(unify(out,ARG3));
 }