diff --git a/src/jtag/drivers/vsllink.c b/src/jtag/drivers/vsllink.c
index 1c0c3e1ee..b9bda5d1e 100644
--- a/src/jtag/drivers/vsllink.c
+++ b/src/jtag/drivers/vsllink.c
@@ -302,7 +302,7 @@ static int vsllink_init(void)
 	}
 
 	/* malloc buffer size for tap */
-	tap_buffer_size = versaloon_interface.usb_setting.buf_size - 32;
+	tap_buffer_size = versaloon_interface.usb_setting.buf_size / 2 - 32;
 	vsllink_free_buffer();
 	tdi_buffer = (uint8_t *)malloc(tap_buffer_size);
 	tdo_buffer = (uint8_t *)malloc(tap_buffer_size);