diff --git a/User/main.c b/User/main.c
index 53c22f4..a6c64b3 100644
--- a/User/main.c
+++ b/User/main.c
@@ -36,7 +36,7 @@ int main(void)
     NVIC_PriorityGroupConfig(NVIC_PriorityGroup_2);
     Delay_Init();
     USART_Printf_Init(115200);
-    printf("SystemClk:%d\r\n", SystemCoreClock);
+    printf("SystemClk:%ld\r\n", SystemCoreClock);
 
     printf("This is printf example\r\n");