diff --git a/src/SerialFake.h b/src/SerialFake.h
index 962148a..a4cc725 100644
--- a/src/SerialFake.h
+++ b/src/SerialFake.h
@@ -4,6 +4,8 @@
 #include "StreamFake.h"
 #include "arduino/USBAPI.h"
 
+#if defined(USBCON)
+
 struct SerialFake : public StreamFake
 {
     virtual void begin(unsigned long) = 0;
@@ -45,4 +47,6 @@ class SerialFakeProxy : public StreamFakeProxy, public Serial_
         {
             return serialFake;
         }
-};
\ No newline at end of file
+};
+
+#endif // USBCON