diff --git a/programs/ssl/dtls_server.c b/programs/ssl/dtls_server.c
index 3ad10ce..69da1d3 100644
--- a/programs/ssl/dtls_server.c
+++ b/programs/ssl/dtls_server.c
@@ -167,7 +167,7 @@
     printf( "  . Bind on udp/*/4433 ..." );
     fflush( stdout );
 
-    if( ( ret = mbedtls_net_bind( &listen_fd, NULL, 4433, MBEDTLS_NET_PROTO_UDP ) ) != 0 )
+    if( ( ret = mbedtls_net_bind( &listen_fd, NULL, "4433", MBEDTLS_NET_PROTO_UDP ) ) != 0 )
     {
         printf( " failed\n  ! mbedtls_net_bind returned %d\n\n", ret );
         goto exit;
@@ -274,7 +274,7 @@
     }
 
     /* With UDP, bind_fd is hijacked by client_fd, so bind a new one */
-    if( ( ret = mbedtls_net_bind( &listen_fd, NULL, 4433, MBEDTLS_NET_PROTO_UDP ) ) != 0 )
+    if( ( ret = mbedtls_net_bind( &listen_fd, NULL, "4433", MBEDTLS_NET_PROTO_UDP ) ) != 0 )
     {
         printf( " failed\n  ! mbedtls_net_bind returned -0x%x\n\n", -ret );
         goto exit;