diff --git a/shadowsocks-libev.sh b/shadowsocks-libev.sh
index 4e13a70..08806fa 100644
--- a/shadowsocks-libev.sh
+++ b/shadowsocks-libev.sh
@@ -15,6 +15,9 @@ cur_dir=`pwd`
 libsodium_file="libsodium-1.0.12"
 libsodium_url="https://github.com/jedisct1/libsodium/releases/download/1.0.12/libsodium-1.0.12.tar.gz"
 
+mbedtls_file="mbedtls-2.5.1"
+mbedtls_url="https://tls.mbed.org/download/mbedtls-2.5.1-gpl.tgz"
+
 # Make sure only root can run our script
 rootness(){
     if [[ $EUID -ne 0 ]]; then
@@ -245,28 +248,58 @@ pre_install(){
     char=`get_char`
     #Install necessary dependencies
     yum install -y epel-release
-    yum install -y gcc gettext-devel unzip autoconf automake make zlib-devel libtool xmlto asciidoc udns-devel libev-devel
-    yum install -y pcre pcre-devel perl perl-devel cpio expat-devel openssl-devel mbedtls-devel
+    yum install -y gcc gettext-devel unzip autoconf automake make zlib-devel libtool udns-devel libev-devel
+    yum install -y pcre pcre-devel perl perl-devel cpio expat-devel openssl-devel
+}
+
+download() {
+    local filename=$(basename $1)
+    if [ -f ${1} ]; then
+        echo "${filename} [found]"
+    else
+        echo "${filename} not found, download now..."
+        wget --no-check-certificate -c -t3 -T60 -O ${1} ${2}
+        if [ $? -ne 0 ]; then
+            echo "Error: Download ${filename} failed."
+            exit 1
+        fi
+    fi
 }
 
 # Download latest shadowsocks-libev
 download_files(){
     cd ${cur_dir}
 
-    if ! wget --no-check-certificate -O ${shadowsocks_libev_ver}.tar.gz ${download_link}; then
-        echo "Failed to download ${shadowsocks_libev_ver}.tar.gz"
-        exit 1
-    fi
+    download "${shadowsocks_libev_ver}.tar.gz" "${download_link}"
+    download "${libsodium_file}.tar.gz" "${libsodium_url}"
+    download "${mbedtls_file}-gpl.tgz" "${mbedtls_url}"
+    download "/etc/init.d/shadowsocks" "${init_script_link}"
+}
 
-    if ! wget --no-check-certificate -O ${libsodium_file}.tar.gz ${libsodium_url}; then
-        echo "Failed to download ${libsodium_file}.tar.gz"
-        exit 1
+install_libsodium() {
+    if [ ! -f /usr/lib/libsodium.a ]; then
+        cd ${cur_dir}
+        tar zxf ${libsodium_file}.tar.gz
+        cd ${libsodium_file}
+        ./configure --prefix=/usr && make && make install
+        if [ $? -ne 0 ]; then
+            echo "Error: ${libsodium_file} install failed."
+            exit 1
+        fi
+    else
+        echo "Info: ${libsodium_file} already installed."
     fi
+}
 
-    # Download init script
-    if ! wget --no-check-certificate -O /etc/init.d/shadowsocks ${init_script_link}; then
-        echo "Failed to download shadowsocks-libev init script!"
-        exit 1
+install_mbedtls() {
+    if [ ! -f /usr/lib/libmbedtls.a ]; then
+        cd ${cur_dir}
+        tar xf ${mbedtls_file}-gpl.tgz
+        cd ${mbedtls_file}
+        make SHARED=1 CFLAGS=-fPIC
+        make DESTDIR=/usr install
+    else
+        echo "Info: ${mbedtls_file} already installed."
     fi
 }
 
@@ -334,22 +367,14 @@ firewall_set(){
 
 # Install Shadowsocks-libev
 install_shadowsocks(){
-    if [ ! -f /usr/lib/libsodium.a ]; then
-        cd ${cur_dir}
-        tar zxf ${libsodium_file}.tar.gz
-        cd ${libsodium_file}
-        ./configure --prefix=/usr && make && make install
-        if [ $? -ne 0 ]; then
-            echo "${libsodium_file} install failed!"
-            exit 1
-        fi
-    fi
+    install_libsodium
+    install_mbedtls
 
     ldconfig
     cd ${cur_dir}
     tar zxf ${shadowsocks_libev_ver}.tar.gz
     cd ${shadowsocks_libev_ver}
-    ./configure
+    ./configure --disable-documentation
     make && make install
     if [ $? -eq 0 ]; then
         chmod +x /etc/init.d/shadowsocks