diff --git a/package-puzzles b/package-puzzles
index 3141fb8..344d85a 100755
--- a/package-puzzles
+++ b/package-puzzles
@@ -1,20 +1,20 @@
 #!/usr/bin/env python3
 
 import argparse
-import base64
+import binascii
 import glob
 import hashlib
-import hmac
 import io
 import json
 import os
-import markdown
-import random
+import shutil
 import sys
 import zipfile
 
 import puzzles
 
+TMPFILE = "%s.tmp"
+
 def write_kv_pairs(ziphandle, filename, kv):
     """ Write out a sorted map to file
     :param ziphandle: a zipfile object
@@ -34,7 +34,6 @@ def write_kv_pairs(ziphandle, filename, kv):
    
 if __name__ == '__main__':        
     parser = argparse.ArgumentParser(description='Build a category package')
-    parser.add_argument('seed', help='contest seed')
     parser.add_argument('categorydirs', nargs='+', help='Directory of category source')
     parser.add_argument('outdir', help='Output directory')
     args = parser.parse_args()
@@ -45,22 +44,20 @@ if __name__ == '__main__':
 
         categoryname = os.path.basename(categorydir.strip(os.sep))
         
-        # build category seed
-        category_seed = hashlib.new('sha1')
-        category_seed.update(categoryname.encode('utf-8'))
-        category_seed.update(args.seed.encode('utf-8'))
-        category_seed = category_seed.hexdigest()
-
         # create zipfile
         zipfilename = os.path.join(args.outdir, "%s.zip" % categoryname)
         if os.path.exists(zipfilename):
-    # assume blank state for now
-            pass
-    #        # open and gather some state
-    #        zf = zipfile.ZipFile(zipfilename, 'a')
-        else:
-            # create and read in state
-            zf = zipfile.ZipFile(zipfilename, 'w')
+            # open and gather some state
+            zf = zipfile.ZipFile(zipfilename, 'r')
+            try:
+                category_seed = zf.open(os.path.join(categoryname, "category_seed.txt")).read().strip()
+            except:
+                pass
+            zf.close()
+
+        zf = zipfile.ZipFile(TMPFILE % zipfilename, 'w')
+        if 'category_seed' not in locals():
+            category_seed =  binascii.b2a_hex(os.urandom(20))
 
         # read in category details (will be pflarr in future)
         for categorypath in glob.glob(os.path.join(categorydir, "*", "puzzle.moth")):
@@ -81,18 +78,18 @@ if __name__ == '__main__':
         summary = {}
         for points in sorted(puzzles_dict):
             puzzle = puzzles_dict[points]
-            hashmap = hashlib.sha1(args.seed.encode('utf-8'))
-            hashmap.update(categoryname.encode('utf-8'))
+            hashmap = hashlib.sha1(category_seed)
             hashmap.update(str(points).encode('utf-8'))
             mapping[points] = hashmap.hexdigest()
             answers[points] = puzzle['answer']
             if len(puzzle['summary']) > 0:
                 summary[points] = puzzle['summary']
 
-        # write mapping, answers, and summary
+        # write mapping, answers, summary, category_seed
         write_kv_pairs(zf, os.path.join(categoryname, 'map.txt'), mapping)
         write_kv_pairs(zf, os.path.join(categoryname, 'answers.txt'), answers)
         write_kv_pairs(zf, os.path.join(categoryname, 'summary.txt'), summary)
+        zf.writestr(os.path.join(categoryname, "category_seed.txt"), category_seed)
 
         # write out puzzles
         for points in sorted(puzzles_dict):
@@ -114,4 +111,8 @@ if __name__ == '__main__':
             # non-optimal writing of file-like objects, but it works
             zf.writestr(os.path.join(puzzledir, 'puzzle.json'), \
                                     json.dumps(puzzle.publish()))
+        
+        # clean up
+        zf.close()
+        shutil.move(TMPFILE % zipfilename, zipfilename)
 #vim:py