diff --git a/cpu/stm32/cpu_init.c b/cpu/stm32/cpu_init.c
index 8087f113746d3..844af39986328 100644
--- a/cpu/stm32/cpu_init.c
+++ b/cpu/stm32/cpu_init.c
@@ -161,6 +161,7 @@ static void _gpio_init_ain(void)
  * This very teniously avoids optimization, even optimized it's better than
  * nothing but periodic review should establish that it doesn't get optimized.
  */
+#if defined(STM32_OPTION_BYTES)
 __attribute__((always_inline))
 static inline uint32_t _multi_read_reg32(volatile uint32_t *addr, bool *glitch)
 {
@@ -242,7 +243,6 @@ static inline uint32_t _multi_read_reg32(volatile uint32_t *addr, bool *glitch)
  */
 
 /* RDP only defined for particular families. Kconfig sets this as necessary */
-#if defined(STM32_OPTION_BYTES)
 
 #ifndef CONFIG_STM32_RDP
 #define CONFIG_STM32_RDP 0