diff --git a/src/x9d/board_x9d.cpp b/src/x9d/board_x9d.cpp
index b2568676c..8c5148e90 100644
--- a/src/x9d/board_x9d.cpp
+++ b/src/x9d/board_x9d.cpp
@@ -38,10 +38,6 @@ uint8_t temperature = 0;          // Raw temp reading
 uint8_t maxTemperature = 0 ;       // Raw temp reading
 volatile uint32_t Tenms ; // TODO to remove everywhere / use a #define
 
-uint32_t Peri1_frequency = 30000000;
-uint32_t Peri2_frequency = 30000000;
-uint32_t Timer_mult = 2;
-
 #define PIN_MODE_MASK           0x0003
 #define PIN_INPUT               0x0000
 #define PIN_OUTPUT              0x0001
@@ -125,7 +121,7 @@ void init5msTimer()
   // Timer14
   RCC->APB1ENR |= RCC_APB1ENR_TIM14EN ;           // Enable clock
   TIM14->ARR = 4999 ;     // 5mS
-  TIM14->PSC = (Peri1_frequency * Timer_mult) / 1000000 - 1 ;                // 1uS from 30MHz
+  TIM14->PSC = (PERI1_FREQUENCY * TIMER_MULT) / 1000000 - 1 ;                // 1uS from 30MHz
   TIM14->CCER = 0 ;
   TIM14->CCMR1 = 0 ;
   TIM14->EGR = 0 ;
diff --git a/src/x9d/board_x9d.h b/src/x9d/board_x9d.h
index 111d00a7e..4a84c6bf3 100644
--- a/src/x9d/board_x9d.h
+++ b/src/x9d/board_x9d.h
@@ -47,10 +47,9 @@
 #include "audio_driver.h"
 #include "delays.h"
 
-extern uint32_t SystemCoreClock;
-extern uint32_t Peri1_frequency;
-extern uint32_t Peri2_frequency;
-extern uint32_t Timer_mult;
+#define PERI1_FREQUENCY 30000000
+#define PERI2_FREQUENCY 60000000
+#define TIMER_MULT 2
 
 // TODO elsewhere
 #if !defined(SIMU)
diff --git a/src/x9d/delays.cpp b/src/x9d/delays.cpp
index 4de5cfd1f..b113e00c7 100644
--- a/src/x9d/delays.cpp
+++ b/src/x9d/delays.cpp
@@ -37,7 +37,7 @@ void delaysInit(void)
 {
   // Timer13
   RCC->APB1ENR |= RCC_APB1ENR_TIM13EN;           // Enable clock
-  TIM13->PSC = (Peri1_frequency * Timer_mult) / 10000000 - 1;      // 0.1uS 
+  TIM13->PSC = (PERI1_FREQUENCY * TIMER_MULT) / 10000000 - 1;      // 0.1uS 
   TIM13->CCER = 0;
   TIM13->CCMR1 = 0;
   TIM13->CR1 = 0x02;