diff --git a/fs/buffer.c b/fs/buffer.c
index 22ed55198f3dca8ab1006051eb734b2e7a3d4ce7..189efa4efc6ede2d5b9e5c3703f4004abe9655e6 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -2211,8 +2211,8 @@ int generic_cont_expand_simple(struct inode *inode, loff_t size)
 	return err;
 }
 
-int cont_expand_zero(struct file *file, struct address_space *mapping,
-			loff_t pos, loff_t *bytes)
+static int cont_expand_zero(struct file *file, struct address_space *mapping,
+			    loff_t pos, loff_t *bytes)
 {
 	struct inode *inode = mapping->host;
 	unsigned blocksize = 1 << inode->i_blkbits;