diff --git a/socket/socket_tcp4.c b/socket/socket_tcp4.c
index 9f72a31..c19a2b3 100644
--- a/socket/socket_tcp4.c
+++ b/socket/socket_tcp4.c
@@ -4,6 +4,7 @@
 
 int socket_tcp4(void) {
   int s=socket_tcp4b();
+  if (s==-1) return -1;
   if (ndelay_on(s) == -1) { close(s); return -1; }
   return s;
 }
diff --git a/socket/socket_tcp6.c b/socket/socket_tcp6.c
index d2b2961..5fc2724 100644
--- a/socket/socket_tcp6.c
+++ b/socket/socket_tcp6.c
@@ -4,6 +4,7 @@
 
 int socket_tcp6(void) {
   int s=socket_tcp6b();
+  if (s==-1) return -1;
   if (ndelay_on(s) == -1) { close(s); return -1; }
   return s;
 }