diff --git a/src/ax25.c b/src/ax25.c
index f123537..162843b 100644
--- a/src/ax25.c
+++ b/src/ax25.c
@@ -76,7 +76,7 @@ int patty_ax25_pton(const char *callsign,
     }
 
     while (o < PATTY_AX25_CALLSIGN_LEN) {
-        addr->callsign[o++] = ' ';
+        addr->callsign[o++] = ' ' << 1;
     }
 
     addr->ssid = (ssid & 0x0f) << 1;