Issue #3366: Add expm1 function to math module.  Thanks Eric Smith for
testing on Windows.
diff --git a/setup.py b/setup.py
index d7ef51e..6b8ffc4 100644
--- a/setup.py
+++ b/setup.py
@@ -414,7 +414,7 @@
                                libraries=math_libs) )
 
         # math library functions, e.g. sin()
-        exts.append( Extension('math',  ['mathmodule.c'],
+        exts.append( Extension('math',  ['mathmodule.c', '_math.c'],
                                libraries=math_libs) )
         # fast string operations implemented in C
         exts.append( Extension('strop', ['stropmodule.c']) )