diff --git a/arch/arm/src/stm32f7/stm32_ethernet.c b/arch/arm/src/stm32f7/stm32_ethernet.c
index 90ba62ab81f..475a2dcec8a 100644
--- a/arch/arm/src/stm32f7/stm32_ethernet.c
+++ b/arch/arm/src/stm32f7/stm32_ethernet.c
@@ -3130,7 +3130,9 @@ static inline int stm32_dm9161(struct stm32_ethmac_s *priv)
 
 static int stm32_phyinit(struct stm32_ethmac_s *priv)
 {
+#ifdef CONFIG_STM32F7_AUTONEG
   volatile uint32_t timeout;
+#endif
   uint32_t regval;
   uint16_t phyval;
   int ret;