diff --git a/sim_disk.c b/sim_disk.c
index 4d3c096e..5a9d779c 100644
--- a/sim_disk.c
+++ b/sim_disk.c
@@ -1732,12 +1732,13 @@ if (capac && (capac != (t_offset)-1)) {
             }
         }
     else {
-        if ((filesystem_capac != (t_offset)-1) &&
-            (filesystem_capac > capac))
-            capac = filesystem_capac;
-        if ((capac != (((t_offset)uptr->capac)*ctx->capac_factor*((dptr->flags & DEV_SECTORS) ? 512 : 1))) || 
-            (DKUF_F_STD != DK_GET_FMT (uptr)))
-            uptr->capac = (t_addr)(capac/(ctx->capac_factor*((dptr->flags & DEV_SECTORS) ? 512 : 1)));
+        if ((filesystem_capac != (t_offset)-1) &&           /* Known file system data size AND */
+            (filesystem_capac > capac))                     /* Data size greater than container size? */
+            capac = filesystem_capac;                       /* Use file system data size */
+        if ((filesystem_capac != (t_offset)-1) &&           /* Known file system data size AND */
+            (capac > (((t_offset)uptr->capac)*ctx->capac_factor*((dptr->flags & DEV_SECTORS) ? 512 : 1))) || /* Data > current size */
+            (DKUF_F_STD != DK_GET_FMT (uptr)))              /* OR ! autosizeable disk */
+            uptr->capac = (t_addr)(capac/(ctx->capac_factor*((dptr->flags & DEV_SECTORS) ? 512 : 1)));  /* update current size */
         }
     }