diff --git a/repos/libports/ports/lwip.hash b/repos/libports/ports/lwip.hash
index f9c9f06dc6..4a8dce138c 100644
--- a/repos/libports/ports/lwip.hash
+++ b/repos/libports/ports/lwip.hash
@@ -1 +1 @@
-cbf1fff1bec6b6033825f81d863bdcd1a6060ed5
+d84dafd43c71b0c325246801d7f2f5ee8ec7bbd9
diff --git a/repos/libports/ports/lwip.port b/repos/libports/ports/lwip.port
index f42b86716c..dc6e6f0bea 100644
--- a/repos/libports/ports/lwip.port
+++ b/repos/libports/ports/lwip.port
@@ -16,7 +16,8 @@ PATCHES := $(addprefix src/lib/lwip/,window_scaling.patch \
                                      sockets_c_errno.patch \
                                      sol_socket_definition.patch \
                                      remove_warnings.patch \
-                                     api_msg.patch)
+                                     api_msg.patch \
+                                     nonblocking_connect.patch)
 
 PATCH_OPT := -p1 -d src/lib/lwip
 
diff --git a/repos/libports/src/lib/lwip/nonblocking_connect.patch b/repos/libports/src/lib/lwip/nonblocking_connect.patch
new file mode 100644
index 0000000000..2d9eec21bb
--- /dev/null
+++ b/repos/libports/src/lib/lwip/nonblocking_connect.patch
@@ -0,0 +1,26 @@
+Avoid assertion on nonblocking connect()
+
+From: Christian Prochaska <christian.prochaska@genode-labs.com>
+
+When calling 'connect()' in nonblocking mode and the connection has been
+established, don't call 'tcp_connect()' again, which would trigger an
+assertion with the message 'tcp_connect: can only connect from state
+CLOSED'.
+---
+ src/api/api_msg.c |    3 ++-
+ 1 file changed, 2 insertions(+), 1 deletion(-)
+
+diff --git a/src/api/api_msg.c b/src/api/api_msg.c
+index c00222c..d05a5ae 100644
+--- a/src/api/api_msg.c
++++ b/src/api/api_msg.c
+@@ -1008,7 +1008,8 @@ lwip_netconn_do_connect(struct api_msg_msg *msg)
+ #if LWIP_TCP
+     case NETCONN_TCP:
+       /* Prevent connect while doing any other action. */
+-      if (msg->conn->state != NETCONN_NONE) {
++      if ((msg->conn->state != NETCONN_NONE) ||
++          ((msg->conn->pcb.tcp->state == ESTABLISHED) && netconn_is_nonblocking(msg->conn))) {
+         msg->err = ERR_ISCONN;
+       } else {
+         setup_tcp(msg->conn);