diff --git a/CHANGES.rst b/CHANGES.rst
index 4da9f72..7b626e7 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -1,6 +1,12 @@
 ``persistent`` Changelog
 ========================
 
+4.2.1 (TBD)
+-----------
+
+- Fix the hashcode of C ``TimeStamp`` objects on 64-bit Python 3 on
+  Windows.
+
 4.2.0 (2016-05-05)
 ------------------
 
diff --git a/appveyor.yml b/appveyor.yml
index 5f1626f..23a8a4c 100644
--- a/appveyor.yml
+++ b/appveyor.yml
@@ -6,8 +6,11 @@ environment:
     - python : 27
     - python : 27-x64
     - python : 33
+    - python : 33-x64
     - python : 34
-    - python : 35	
+    - python : 34-x64
+    - python : 35
+    - python : 35-x64
 
 install:
   - "SET PATH=C:\\Python%PYTHON%;c:\\Python%PYTHON%\\scripts;%PATH%"
diff --git a/persistent/_timestamp.c b/persistent/_timestamp.c
index 83bcdf8..63ced30 100644
--- a/persistent/_timestamp.c
+++ b/persistent/_timestamp.c
@@ -152,7 +152,12 @@ TimeStamp_richcompare(TimeStamp *self, TimeStamp *other, int op)
     return result;
 }
 
+
+#ifdef PY3K
+static Py_hash_t
+#else
 static long
+#endif
 TimeStamp_hash(TimeStamp *self)
 {
     register unsigned char *p = (unsigned char *)self->data;