Index: msi.py
===================================================================
--- msi.py	(revision 74586)
+++ msi.py	(working copy)
@@ -175,8 +175,16 @@
 # Determine the target architechture
 dll_path = os.path.join(srcdir, PCBUILD, dll_file)
 msilib.set_arch_from_file(dll_path)
-if msilib.pe_type(dll_path) != msilib.pe_type("msisupport.dll"):
-    raise SystemError("msisupport.dll for incorrect architecture")
+have_msisupport = os.path.exists("msisupport.dll")
+if have_msisupport:
+    try:
+        if msilib.pe_type(dll_path) != msilib.pe_type("msisupport.dll"):
+            raise SystemError("msisupport.dll for incorrect architecture")
+    except:
+        print("WARNING: Architecture check for msisupport.dll failed.")
+else:
+    print("WARNING: msisupport.dll not found. Architecture check for msisupport.dll skipped.")
+
 if msilib.Win64:
     upgrade_code = upgrade_code_64
     # Bump the last digit of the code by one, so that 32-bit and 64-bit