diff --git a/reactos/include/ddk/iotypes.h b/reactos/include/ddk/iotypes.h
index 3af6fc71fdf..bca07696b55 100644
--- a/reactos/include/ddk/iotypes.h
+++ b/reactos/include/ddk/iotypes.h
@@ -196,6 +196,8 @@ typedef struct _CM_MCA_POS_DATA
 } CM_MCA_POS_DATA, *PCM_MCA_POS_DATA;
 
 
+#include <pshpack1.h>
+
 /* Int13 drive geometry data */
 
 typedef struct _CM_INT13_DRIVE_PARAMETER
@@ -207,6 +209,8 @@ typedef struct _CM_INT13_DRIVE_PARAMETER
   USHORT NumberDrives;
 } CM_INT13_DRIVE_PARAMETER, *PCM_INT13_DRIVE_PARAMETER;
 
+#include <poppack.h>
+
 
 /* Extended drive geometry data */