diff --git a/drivers/mfd/aat2870-core.c b/drivers/mfd/aat2870-core.c
index 345dc65..02c4201 100644
--- a/drivers/mfd/aat2870-core.c
+++ b/drivers/mfd/aat2870-core.c
@@ -295,7 +295,7 @@
 {
 	struct aat2870_data *aat2870 = file->private_data;
 	char buf[32];
-	int buf_size;
+	ssize_t buf_size;
 	char *start = buf;
 	unsigned long addr, val;
 	int ret;