diff --git a/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan_crypto.c b/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan_crypto.c
index 18fc6e29b9..1109eb9a9d 100644
--- a/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan_crypto.c
+++ b/sys/net/gnrc/link_layer/lorawan/gnrc_lorawan_crypto.c
@@ -50,7 +50,7 @@ typedef struct __attribute__((packed)) {
     union {
         uint32_t u8_pad;
         le_uint16_t conf_fcnt;
-    };
+    }__attribute__((packed));
     uint8_t dir;
     le_uint32_t dev_addr;
     le_uint32_t fcnt;