diff --git a/src/default_lowlevel.h b/src/default_lowlevel.h
index fc58c9cb8..fcab1cfcb 100644
--- a/src/default_lowlevel.h
+++ b/src/default_lowlevel.h
@@ -1,8 +1,8 @@
 #ifndef LOWLEVEL_H
 #define LOWLEVEL_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);
 
 #endif
diff --git a/tests/rftest-rx.c b/tests/rftest-rx.c
index 20550a044..3bf2a9f5b 100644
--- a/tests/rftest-rx.c
+++ b/tests/rftest-rx.c
@@ -23,7 +23,7 @@ void main(void) {
 	*GPIO_DATA_SEL0 = ( 1 << LED ); 
 
 	/* trim the reference osc. to 24MHz */
-	pack_XTAL_CNTL(CTUNE_4PF, CTUNE, FTUNE, IBIAS);
+	trim_xtal();
 
 	uart_init(INC, MOD, SAMP);
 
diff --git a/tests/rftest-tx.c b/tests/rftest-tx.c
index b77f84679..971f68b17 100644
--- a/tests/rftest-tx.c
+++ b/tests/rftest-tx.c
@@ -33,7 +33,7 @@ void main(void) {
 	volatile packet_t *p;
 
 	/* trim the reference osc. to 24MHz */
-	pack_XTAL_CNTL(CTUNE_4PF, CTUNE, FTUNE, IBIAS);
+	trim_xtal();
 
 	uart_init(INC, MOD, SAMP);