diff --git a/base/bootstrap.sh b/base/bootstrap.sh
index 54c44e3..c97aefa 100755
--- a/base/bootstrap.sh
+++ b/base/bootstrap.sh
@@ -2,13 +2,16 @@
 
 if ! [[ -z "${repo}" ]]; then
   if [[ -z "${branch}" ]]; then
-    git clone $repo workspace
+    git clone $repo /workspace
   else
     git clone -b $branch $repo /workspace
   fi
 fi
 
-cd /workspace
+if [ -d /workspace ]; then
+  cd /workspace
+fi
 
-$@
+# use eval because commands likes `key=value command` would cause file not found error when using $@, but this eval will ruin current environment
+eval $@
 
diff --git a/python3/Dockerfile b/python3/Dockerfile
index a97492c..b351e67 100644
--- a/python3/Dockerfile
+++ b/python3/Dockerfile
@@ -5,5 +5,6 @@ MAINTAINER Newnius <newnius.cn@gmail.com>
 USER root
 
 RUN apt update && \
-	apt install -y python3 python3-pip
+	apt install -y python3 python3-pip && \
+	rm -rf /var/lib/apt/lists/*