diff --git a/sam3s_example/simtrace/simtrace.h b/sam3s_example/simtrace/simtrace.h
index 444e783..0e024e9 100644
--- a/sam3s_example/simtrace/simtrace.h
+++ b/sam3s_example/simtrace/simtrace.h
@@ -1,3 +1,5 @@
+#ifndef SIMTRACE_H
+#define SIMTRACE_H
 
 // FIXME: static function definitions
 extern uint32_t _ISO7816_GetChar( uint8_t *pCharToReceive );
@@ -6,4 +8,8 @@
 
 extern void Sniffer_Init( void );
 
+extern void SIMtrace_USB_Initialize( void );
 
+extern void _ISO7816_Init( void );
+
+#endif