diff --git a/reactos/include/ndk/rtltypes.h b/reactos/include/ndk/rtltypes.h
index fd9724d0c96..8f0afbd19da 100644
--- a/reactos/include/ndk/rtltypes.h
+++ b/reactos/include/ndk/rtltypes.h
@@ -40,6 +40,7 @@ Author:
 #define RTL_USER_PROCESS_PARAMETERS_PROFILE_KERNEL          0x08
 #define RTL_USER_PROCESS_PARAMETERS_UNKNOWN                 0x10
 #define RTL_USER_PROCESS_PARAMETERS_RESERVE_1MB             0x20
+#define RTL_USER_PROCESS_PARAMETERS_RESERVE_16MB            0x40
 #define RTL_USER_PROCESS_PARAMETERS_DISABLE_HEAP_CHECKS     0x100
 #define RTL_USER_PROCESS_PARAMETERS_PROCESS_OR_1            0x200
 #define RTL_USER_PROCESS_PARAMETERS_PROCESS_OR_2            0x400