diff --git a/setup.py b/setup.py
index cc163ea..8309008 100644
--- a/setup.py
+++ b/setup.py
@@ -315,7 +315,7 @@
         # time operations and variables
         exts.append( Extension('time', ['timemodule.c'],
                                libraries=math_libs) )
-        exts.append( Extension('datetime', ['datetimemodule.c'],
+        exts.append( Extension('datetime', ['datetimemodule.c', 'timemodule.c'],
                                libraries=math_libs) )
         # random number generator implemented in C
         exts.append( Extension("_random", ["_randommodule.c"]) )