diff --git a/arch/sandbox/cpu/os.c b/arch/sandbox/cpu/os.c
index 873f85a..6837bfc 100644
--- a/arch/sandbox/cpu/os.c
+++ b/arch/sandbox/cpu/os.c
@@ -638,7 +638,7 @@
 
 void os_putc(int ch)
 {
-	putchar(ch);
+	fputc(ch, stdout);
 }
 
 void os_puts(const char *str)