diff --git a/include/patty/ax25.h b/include/patty/ax25.h
index a098f04..2d86904 100644
--- a/include/patty/ax25.h
+++ b/include/patty/ax25.h
@@ -42,7 +42,7 @@ enum patty_ax25_proto {
 #pragma pack(1)
 
 typedef struct _patty_ax25_addr {
-    char callsign[6];
+    char callsign[PATTY_AX25_CALLSIGN_LEN];
     uint8_t ssid;
 } patty_ax25_addr;