diff --git a/components/finsh/shell.c b/components/finsh/shell.c
index 61c8d3dd15..1033e2c998 100644
--- a/components/finsh/shell.c
+++ b/components/finsh/shell.c
@@ -139,7 +139,7 @@ static int finsh_getchar(void)
 #ifdef RT_USING_POSIX
     return getchar();
 #else
-    int ch;
+    int ch = 0;
 
     RT_ASSERT(shell != RT_NULL);
     while (rt_device_read(shell->device, -1, &ch, 1) != 1)