diff --git a/reactos/include/reactos/arm/armddk.h b/reactos/include/reactos/arm/armddk.h
index 31a6cca720b..70aa86caae1 100644
--- a/reactos/include/reactos/arm/armddk.h
+++ b/reactos/include/reactos/arm/armddk.h
@@ -16,6 +16,13 @@
 #define POWER_LEVEL                       30
 #define HIGH_LEVEL                        31
 
+//
+// Page size
+//
+#ifndef PAGE_SIZE
+#define PAGE_SIZE 0x1000
+#endif
+
 //
 // FIXME: mmtypes.h?
 //