diff --git a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/spi_api.c b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/spi_api.c
index 0355e89ba1..722dd9bdc3 100644
--- a/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/spi_api.c
+++ b/libraries/mbed/targets/hal/TARGET_Silicon_Labs/TARGET_EFM32/spi_api.c
@@ -50,7 +50,7 @@
 static uint16_t fill_word = SPI_FILL_WORD;
 #define SPI_LEAST_ACTIVE_SLEEPMODE EM1
 
-inline CMU_Clock_TypeDef spi_get_clock_tree(spi_t *obj)
+static inline CMU_Clock_TypeDef spi_get_clock_tree(spi_t *obj)
 {
     switch ((int)obj->spi.spi) {
 #ifdef USART0
@@ -71,7 +71,7 @@ inline CMU_Clock_TypeDef spi_get_clock_tree(spi_t *obj)
     }
 }
 
-inline uint8_t spi_get_index(spi_t *obj)
+static inline uint8_t spi_get_index(spi_t *obj)
 {
     uint8_t index = 0;
     switch ((int)obj->spi.spi) {