diff --git a/test/unit/arch/sys_arch.c b/test/unit/arch/sys_arch.c
index cf826ebf..ed0e34f0 100644
--- a/test/unit/arch/sys_arch.c
+++ b/test/unit/arch/sys_arch.c
@@ -365,7 +365,23 @@ sys_arch_mbox_tryfetch(sys_mbox_t *q, void **msg)
 }
 
 #if LWIP_NETCONN_SEM_PER_THREAD
-#error LWIP_NETCONN_SEM_PER_THREAD==1 not supported
+/* Simple implementation of this: unit tests only support one thread */
+static sys_sem_t global_netconn_sem;
+
+sys_sem_t* sys_arch_netconn_sem_get(void)
+{
+  return &global_netconn_sem;
+}
+
+void sys_arch_netconn_sem_alloc(void)
+{
+  sys_sem_new(&global_netconn_sem, 0);
+}
+
+void sys_arch_netconn_sem_free(void)
+{
+  sys_sem_free(&global_netconn_sem);
+}
 #endif /* LWIP_NETCONN_SEM_PER_THREAD */
 
 #endif /* !NO_SYS */
diff --git a/test/unit/arch/sys_arch.h b/test/unit/arch/sys_arch.h
index 331c2f2f..9157b6a8 100644
--- a/test/unit/arch/sys_arch.h
+++ b/test/unit/arch/sys_arch.h
@@ -68,5 +68,12 @@ void test_sys_arch_wait_callback(test_sys_arch_waiting_fn waiting_fn);
 /* current time */
 extern u32_t lwip_sys_now;
 
+sys_sem_t* sys_arch_netconn_sem_get(void);
+void sys_arch_netconn_sem_alloc(void);
+void sys_arch_netconn_sem_free(void);
+#define LWIP_NETCONN_THREAD_SEM_GET()   sys_arch_netconn_sem_get()
+#define LWIP_NETCONN_THREAD_SEM_ALLOC() sys_arch_netconn_sem_alloc()
+#define LWIP_NETCONN_THREAD_SEM_FREE()  sys_arch_netconn_sem_free()
+
 #endif /* LWIP_HDR_TEST_SYS_ARCH_H */
 
diff --git a/test/unit/lwipopts.h b/test/unit/lwipopts.h
index c00ace15..e4523fc1 100644
--- a/test/unit/lwipopts.h
+++ b/test/unit/lwipopts.h
@@ -46,6 +46,7 @@
 #define LWIP_NETCONN                    !NO_SYS
 #define LWIP_SOCKET                     !NO_SYS
 #define LWIP_NETCONN_FULLDUPLEX         LWIP_SOCKET
+#define LWIP_NETCONN_SEM_PER_THREAD     1
 #define LWIP_NETBUF_RECVINFO            1
 #define LWIP_HAVE_LOOPIF                1
 #define TCPIP_THREAD_TEST