diff --git a/include/patty/ax25/call.h b/include/patty/ax25/call.h
index 03c7f4e..e1ba556 100644
--- a/include/patty/ax25/call.h
+++ b/include/patty/ax25/call.h
@@ -64,7 +64,7 @@ int patty_ax25_call_setsockopt(int server,
  */
 typedef struct _patty_ax25_call_bind_request {
     int fd;
-    patty_ax25_addr peer;
+    patty_ax25_addr addr;
 } patty_ax25_call_bind_request;
 
 typedef struct _patty_ax25_call_bind_response {
diff --git a/src/call.c b/src/call.c
index c53fb60..fde3561 100644
--- a/src/call.c
+++ b/src/call.c
@@ -82,7 +82,7 @@ error_io:
 
 int patty_ax25_call_bind(int server,
                          int fd,
-                         patty_ax25_addr *peer) {
+                         patty_ax25_addr *addr) {
     enum patty_ax25_call call = PATTY_AX25_CALL_BIND;
 
     patty_ax25_call_bind_request request = {
@@ -91,7 +91,7 @@ int patty_ax25_call_bind(int server,
 
     patty_ax25_call_bind_response response;
 
-    memcpy(&request.peer, peer, sizeof(*peer));
+    memcpy(&request.addr, addr, sizeof(*addr));
 
     if (write(server, &call, sizeof(call)) < 0) {
         goto error_io;
diff --git a/src/server.c b/src/server.c
index 3d93b4f..9133112 100644
--- a/src/server.c
+++ b/src/server.c
@@ -624,6 +624,20 @@ static int server_bind(patty_ax25_server *server,
         goto error_sock_by_fd;
     }
 
+    if (sock->local.callsign[0] != '\0') {
+        response.ret = -1;
+        response.eno = EINVAL;
+
+        goto error_bound;
+    }
+
+    if (sock_by_addr(server->socks_local, &request.addr) != NULL) {
+        response.ret = -1;
+        response.eno = EADDRINUSE;
+
+        goto error_exists;
+    }
+
     switch (sock->status) {
         case PATTY_AX25_SOCK_LISTENING:
         case PATTY_AX25_SOCK_ESTABLISHED:
@@ -636,12 +650,14 @@ static int server_bind(patty_ax25_server *server,
             break;
     }
 
-    memcpy(&sock->local, &request.peer, sizeof(request.peer));
+    memcpy(&sock->local, &request.addr, sizeof(request.addr));
 
     response.ret = 0;
     response.eno = 0;
 
 error_invalid_status:
+error_exists:
+error_bound:
 error_sock_by_fd:
     return write(client, &response, sizeof(response));