diff --git a/tiff.h b/tiff.h
index bc46acd..78753f7 100644
--- a/tiff.h
+++ b/tiff.h
@@ -75,7 +75,8 @@ typedef TIFF_INT32_T  int32;
 typedef TIFF_UINT32_T uint32;
 
 typedef TIFF_INT64_T  int64;
-typedef TIFF_UINT64_T uint64;
+typedef uint64_t uint64;
+
 
 /*
  * Some types as promoted in a variable argument list
