diff --git a/Inc/main.h b/Inc/main.h
index 88dd48e..6391ab2 100644
--- a/Inc/main.h
+++ b/Inc/main.h
@@ -123,6 +123,7 @@ extern "C" {
 
 // These are no-ops on NucleoTNC.
 void SysClock80(void);
+void SysClock72(void);
 void SysClock48(void);
 void SysClock4(void);