diff --git a/kernel/fs.h b/kernel/fs.h
index 139dcc9c37..05575b5fcd 100644
--- a/kernel/fs.h
+++ b/kernel/fs.h
@@ -51,10 +51,11 @@ struct dinode {
 #define BBLOCK(b, sb) ((b)/BPB + sb.bmapstart)
 
 // Directory is a file containing a sequence of dirent structures.
-#define DIRSIZ 14
+// Setting DIRSIZ to 12 makes sizeof(struct dirent) a multiple of 16.
+#define DIRSIZ 12
 
 struct dirent {
-  ushort inum;
+  uint inum;
   char name[DIRSIZ];
 };