diff --git a/dev.sh b/dev.sh
old mode 100644
new mode 100755
index ca08299..fcce219
--- a/dev.sh
+++ b/dev.sh
@@ -10,7 +10,7 @@ fi
 
 #default snappy and leveldb install path
 #you may change yourself
-HOMEBREW_PREFIX=$(brew --prefix 2>/dev/null)
+HOMEBREW_PREFIX=$(type brew >/dev/null 2>&1 && brew --prefix 2>/dev/null)
 if [[ ! -z "$HOMEBREW_PREFIX" ]]; then
   SNAPPY_DIR=$HOMEBREW_PREFIX/opt/snappy
   LEVELDB_DIR=$HOMEBREW_PREFIX/opt/leveldb