diff --git a/src/default_lowlevel.h b/src/default_lowlevel.h
index cbbab4887..803f94a17 100644
--- a/src/default_lowlevel.h
+++ b/src/default_lowlevel.h
@@ -36,6 +36,8 @@
 #ifndef LOWLEVEL_H
 #define LOWLEVEL_H
 
+#include "crm.h"
+
 #define trim_xtal() pack_XTAL_CNTL(CTUNE_4PF, CTUNE, FTUNE, IBIAS);
 void default_vreg_init(void);
 void uart1_init(uint16_t inc, uint16_t mod, uint8_t samp);