diff --git a/models/recall/word2vec/preprocess.py b/models/recall/word2vec/preprocess.py
index 6c9ee16cd2d136006dc10e7ce0c970974e8bf2b5..679458e388229c5e3b3a8f3d14d212eb1d263544 100755
--- a/models/recall/word2vec/preprocess.py
+++ b/models/recall/word2vec/preprocess.py
@@ -162,7 +162,7 @@ def filter_corpus(args):
                         if r_value > keep_prob:
                             continue
                         write_line += str(idx)
-                        write_line += ","
+                        write_line += " "
                         signal = True
                     if signal:
                         write_line = write_line[:-1] + "\n"