diff --git a/reactos/include/psdk/winuser.h b/reactos/include/psdk/winuser.h
index e8fae73c3a4..f6c15808e83 100644
--- a/reactos/include/psdk/winuser.h
+++ b/reactos/include/psdk/winuser.h
@@ -2501,6 +2501,9 @@ extern "C" {
 #define SW_SCROLLCHILDREN 1
 #define SW_INVALIDATE 2
 #define SW_ERASE 4
+#if(WINVER >= 0x0500)
+#define SW_SMOOTHSCROLL 16
+#endif
 #define SC_SIZE 0xF000
 #define SC_MOVE 0xF010
 #define SC_MINIMIZE 0xF020
diff --git a/reactos/include/reactos/undocuser.h b/reactos/include/reactos/undocuser.h
index c0c6b53a3f5..ab97c39afdc 100644
--- a/reactos/include/reactos/undocuser.h
+++ b/reactos/include/reactos/undocuser.h
@@ -71,6 +71,9 @@
 /* NtUserSetScrollInfo mask to return original position before it is change */
 #define SIF_PREVIOUSPOS 4096
 
+/* ScrollWindow uses the window DC, ScrollWindowEx doesn't */
+#define SW_SCROLLWNDDCE 0x8000
+
 /* Non SDK Queue state flags. */
 #define QS_SMRESULT 0x8000 /* see "Undoc. Windows" */