diff --git a/gensim/similarities/docsim.py b/gensim/similarities/docsim.py
index 4e036d720e..4f7782a402 100755
--- a/gensim/similarities/docsim.py
+++ b/gensim/similarities/docsim.py
@@ -462,7 +462,7 @@ def query_shards(self, query):
         if PARALLEL_SHARDS and PARALLEL_SHARDS > 1:
             logger.debug("spawning %i query processes", PARALLEL_SHARDS)
             pool = multiprocessing.Pool(PARALLEL_SHARDS)
-            result = pool.imap(query_shard, args, chunksize=1 + len(args) / PARALLEL_SHARDS)
+            result = pool.imap(query_shard, args, chunksize=1 + len(list(args)) / PARALLEL_SHARDS)
         else:
             # serial processing, one shard after another
             pool = None