diff --git a/net/ip/net_driver_15_4.c b/net/ip/net_driver_15_4.c
index aa0bd849329..9591c0426b6 100644
--- a/net/ip/net_driver_15_4.c
+++ b/net/ip/net_driver_15_4.c
@@ -49,7 +49,7 @@ static char __noinit __stack rx_fiber_stack[STACKSIZE_UNIT * 1];
 /* The 802.15.4 loopback test app (test_15_4) needs bigger stack. */
 static char __noinit __stack tx_fiber_stack[NET_802154_TX_STACK_SIZE];
 #else
-static char __noinit __stack tx_fiber_stack[STACKSIZE_UNIT * 3 / 2];
+static char __noinit __stack tx_fiber_stack[STACKSIZE_UNIT * 4];
 #endif
 
 /* Queue for incoming packets from hw driver */