diff --git a/rvprof.h b/rvprof.h
index 8ba9ba0..4f63a07 100644
--- a/rvprof.h
+++ b/rvprof.h
@@ -21,6 +21,10 @@ void rvprof_region_end(const char* name);
 // not called by instrumented code direclty anymore
 void rvprof_finalize(void);
 
+// cygnus function hooks
+void __cyg_profile_func_enter(void *this_fn, void *call_site);
+void __cyg_profile_func_exit(void *this_fn, void *call_site);
+
 #ifdef __cplusplus
 extern }
 #endif