diff --git a/fs/nilfs2/inode.c b/fs/nilfs2/inode.c
index 489592644b68..5f2d73f36e0d 100644
--- a/fs/nilfs2/inode.c
+++ b/fs/nilfs2/inode.c
@@ -1267,7 +1267,7 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 			if (size) {
 				if (phys && blkphy << blkbits == phys + size) {
 					/* The current extent goes on */
-					size += n << blkbits;
+					size += (u64)n << blkbits;
 				} else {
 					/* Terminate the current extent */
 					ret = fiemap_fill_next_extent(
@@ -1280,14 +1280,14 @@ int nilfs_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
 					flags = FIEMAP_EXTENT_MERGED;
 					logical = blkoff << blkbits;
 					phys = blkphy << blkbits;
-					size = n << blkbits;
+					size = (u64)n << blkbits;
 				}
 			} else {
 				/* Start a new extent */
 				flags = FIEMAP_EXTENT_MERGED;
 				logical = blkoff << blkbits;
 				phys = blkphy << blkbits;
-				size = n << blkbits;
+				size = (u64)n << blkbits;
 			}
 			blkoff += n;
 		}