diff --git a/mm/filemap.h b/mm/filemap.h
index c2bff04..a1e10a2 100644
--- a/mm/filemap.h
+++ b/mm/filemap.h
@@ -87,7 +87,7 @@
 	const struct iovec *iov = *iovp;
 	size_t base = *basep;
 
-	do {
+	while (bytes) {
 		int copy = min(bytes, iov->iov_len - base);
 
 		bytes -= copy;
@@ -96,7 +96,7 @@
 			iov++;
 			base = 0;
 		}
-	} while (bytes);
+	}
 	*iovp = iov;
 	*basep = base;
 }