diff --git a/src/pst-crc32.h b/src/pst-crc32.h
index fc0f005..8a46201 100644
--- a/src/pst-crc32.h
+++ b/src/pst-crc32.h
@@ -1,7 +1,7 @@
-typedef unsigned int DWORD;
+typedef size_t DWORD;
 typedef unsigned int UINT;
 typedef const void *LPCVOID;
-typedef unsigned int *DWORD_PTR;
+typedef size_t *DWORD_PTR;
 typedef unsigned char byte;
 
 const DWORD CrcTableOffset32[256] = {