diff --git a/build_dict.sh b/build_dict.sh
index a800847..0bf3607 100755
--- a/build_dict.sh
+++ b/build_dict.sh
@@ -4,5 +4,5 @@ KANJIDIC=util/kanjidic
 EDICT=util/edict
 DICT=yomi_base/japanese/dictionary.db
 
-rm $DICT
+[ -f $DICT ] && rm $DICT
 util/compile.py --kanjidic $KANJIDIC --edict $EDICT $DICT
diff --git a/build_zip.sh b/build_zip.sh
index 59116a2..c5311b7 100755
--- a/build_zip.sh
+++ b/build_zip.sh
@@ -1,2 +1,6 @@
 #!/bin/sh
+
+ZIP=yomichan.zip
+
+[ -f $ZIPFILE ] rm $ZIP
 7z a yomichan.zip -xr\!\*.pyc yomichan.py yomi_base