diff --git a/kernel/tasks.c b/kernel/tasks.c
index 2dec1348..413ce994 100644
--- a/kernel/tasks.c
+++ b/kernel/tasks.c
@@ -243,7 +243,9 @@ static int create_task(tid_t* id, internal_entry_point_t ep, void* arg)
 
 			task_table[i].start_heap = 0;
 			task_table[i].end_heap = 0;
+#ifdef CONFIG_LWIP
 			task_table[i].lwip_err = 0;
+#endif
 			task_table[i].start_tick = get_clock_tick();
 			break;
 		}
@@ -309,7 +311,9 @@ int sys_fork(void)
 			task_table[i].start_tick = get_clock_tick();
 			task_table[i].start_heap = 0;
 			task_table[i].end_heap = 0;
+#ifdef CONFIG_LWIP
 			task_table[i].lwip_err = 0;
+#endif
 
 			ret = arch_fork(task_table+i);