Fix yotta examples baud rate.
diff --git a/yotta/data/example-authcrypt/main.cpp b/yotta/data/example-authcrypt/main.cpp
index 83d5566..23fad27 100644
--- a/yotta/data/example-authcrypt/main.cpp
+++ b/yotta/data/example-authcrypt/main.cpp
@@ -175,10 +175,6 @@
 #include "minar/minar.h"
 
 static void run() {
-    /* Use 115200 bps for consistency with other examples */
-    Serial pc(USBTX, USBRX);
-    pc.baud(115200);
-
     MBED_HOSTTEST_TIMEOUT(10);
     MBED_HOSTTEST_SELECT(default);
     MBED_HOSTTEST_DESCRIPTION(mbed TLS example authcrypt);
@@ -187,6 +183,8 @@
 }
 
 void app_start(int, char*[]) {
+    /* Use 115200 bps for consistency with other examples */
+    get_stdio_serial().baud(115200);
     minar::Scheduler::postCallback(mbed::util::FunctionPointer0<void>(run).bind());
 }