1 files changed, 1 insertions, 1 deletions
diff --git a/Makefile b/Makefile
index 398e442..432260b 100644
--- a/Makefile
+++ b/Makefile
@@ -108,7 +108,7 @@ CFLAGS += -DUSE_STDPERIPH_DRIVER -DSTM32F4XX -DSTM32F429xx
 CFLAGS += -D__CORTEX_M4 -DTARGET_STM -DTARGET_STM32F4 -DTARGET_STM32F429ZI -DTOOLCHAIN_GCC -D__FPU_PRESENT=1 -D$(BOARD)
 CFLAGS += -DENABLE_WEAK_FUNCTIONS
 CFLAGS += -ffunction-sections -fdata-sections -Wl,--gc-sections
-CFLAGS += -std=gnu99
+CFLAGS += -std=c99
 CFLAGS += -I$(TOPLEVEL)
 CFLAGS += -I$(MBED_DIR)/api
 CFLAGS += -I$(MBED_DIR)/targets/cmsis