diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c
index 2150edf..6b7474a 100644
--- a/fs/ecryptfs/read_write.c
+++ b/fs/ecryptfs/read_write.c
@@ -87,7 +87,7 @@
 	loff_t offset;
 	int rc;
 
-	offset = ((((off_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
+	offset = ((((loff_t)page_for_lower->index) << PAGE_CACHE_SHIFT)
 		  + offset_in_page);
 	virt = kmap(page_for_lower);
 	rc = ecryptfs_write_lower(ecryptfs_inode, virt, offset, size);