diff --git a/src/api/api_lib.c b/src/api/api_lib.c
index 82b5fda8..d209cb96 100644
--- a/src/api/api_lib.c
+++ b/src/api/api_lib.c
@@ -868,7 +868,14 @@ netconn_gethostbyname(const char *name, ip_addr_t *addr)
   }
 #endif /* LWIP_NETCONN_SEM_PER_THREAD */
 
-  tcpip_callback(lwip_netconn_do_gethostbyname, &API_VAR_REF(msg));
+  err = tcpip_callback(lwip_netconn_do_gethostbyname, &API_VAR_REF(msg));
+  if (err != ERR_OK) {
+#if !LWIP_NETCONN_SEM_PER_THREAD
+    sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
+#endif /* !LWIP_NETCONN_SEM_PER_THREAD */
+    API_VAR_FREE(MEMP_DNS_API_MSG, msg);
+    return err;
+  }
   sys_sem_wait(API_EXPR_REF_SEM(API_VAR_REF(msg).sem));
 #if !LWIP_NETCONN_SEM_PER_THREAD
   sys_sem_free(API_EXPR_REF(API_VAR_REF(msg).sem));
diff --git a/src/api/sockets.c b/src/api/sockets.c
index ac9a71a2..2304c937 100644
--- a/src/api/sockets.c
+++ b/src/api/sockets.c
@@ -1820,7 +1820,12 @@ lwip_getsockopt(int s, int level, int optname, void *optval, socklen_t *optlen)
 #else
   LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = &sock->conn->op_completed;
 #endif
-  tcpip_callback(lwip_getsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));
+  err = tcpip_callback(lwip_getsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));
+  if (err != ERR_OK) {
+    LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
   sys_arch_sem_wait((sys_sem_t*)(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem), 0);
 
   /* write back optlen and optval */
@@ -2224,7 +2229,12 @@ lwip_setsockopt(int s, int level, int optname, const void *optval, socklen_t opt
 #else
   LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem = &sock->conn->op_completed;
 #endif
-  tcpip_callback(lwip_setsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));
+  err = tcpip_callback(lwip_setsockopt_callback, &LWIP_SETGETSOCKOPT_DATA_VAR_REF(data));
+  if (err != ERR_OK) {
+    LWIP_SETGETSOCKOPT_DATA_VAR_FREE(data);
+    sock_set_errno(sock, err_to_errno(err));
+    return -1;
+  }
   sys_arch_sem_wait((sys_sem_t*)(LWIP_SETGETSOCKOPT_DATA_VAR_REF(data).completed_sem), 0);
 
   /* maybe lwip_getsockopt_internal has changed err */