diff --git a/reactos/lib/fslib/vfatlib/fat12.c b/reactos/lib/fslib/vfatlib/fat12.c
index 4b7ac32ad18..032895a4fab 100644
--- a/reactos/lib/fslib/vfatlib/fat12.c
+++ b/reactos/lib/fslib/vfatlib/fat12.c
@@ -289,7 +289,7 @@ Fat12Format(IN HANDLE FileHandle,
     /* Calculate cluster size */
     if (ClusterSize == 0)
     {
-        if (DiskGeometry.MediaType == FixedMedia)
+        if (DiskGeometry->MediaType == FixedMedia)
         {
             /* 4KB Cluster (Harddisk only) */
             ClusterSize = 4096;