diff --git a/src/volser/volint.xg b/src/volser/volint.xg
index 4d20f0a7a2..5febc63308 100644
--- a/src/volser/volint.xg
+++ b/src/volser/volint.xg
@@ -210,9 +210,10 @@ struct pIDs {
 };
 
 struct diskPartition {
-	 char	name[32];	/* Mounted partition name */
-   	 char	devName[32];
-	 int	lock_fd;
+	char	name[32];	/* Mounted partition name */
+   	char	devName[32];
+	int	lock_fd;        /* assigned from DiskPartition FD_t
+                                   which is 64-bit HANDLE on Windows */
 	int	totalUsable;
 	int 	free;
 	int 	minFree;
@@ -220,13 +221,13 @@ struct diskPartition {
 };
 
 struct diskPartition64 {
-    char	name[256];	/* Mounted partition name */
-    char	devName[256];
-    int	        lock_fd;
-    afs_int64	totalUsable;
-    afs_int64 	free;
-    afs_int64 	minFree;
-
+        char	        name[256];	/* Mounted partition name */
+        char	        devName[256];
+        int	        lock_fd;        /* assigned from DiskPartition64 FD_t
+                                           which is a 64-bit HANDLE on Windows */
+        afs_int64	totalUsable;
+        afs_int64 	free;
+        afs_int64 	minFree;
 };
 
 struct restoreCookie {