diff --git a/include/basetsd.h b/include/basetsd.h
index bb6f9be0ef4903a8a6273593a41c555fc567b57e..987d843f6bb57c0ac3dbae6e9a6b20352a0b47f0 100644
--- a/include/basetsd.h
+++ b/include/basetsd.h
@@ -139,6 +139,8 @@ typedef unsigned short UHALF_PTR, *PUHALF_PTR;
 typedef LONG_PTR SSIZE_T, *PSSIZE_T;
 typedef ULONG_PTR SIZE_T, *PSIZE_T;
 
+typedef ULONG_PTR KAFFINITY, *PKAFFINITY;
+
 /* Some Wine-specific definitions */
 
 /* Architecture dependent settings. */