diff --git a/.travis.yml b/.travis.yml
index 086ab81..5be4c36 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,5 +1,9 @@
 sudo: required
-dist: trusty
+dist: focal
+
+branches:
+  only:
+    - "master"
 
 os: linux
 
@@ -7,7 +11,6 @@ language: c
 
 compiler:
   - gcc
-  - clang
 
 env:
   global:
@@ -21,8 +24,7 @@ env:
     - NGX_BUILD_JOBS=$JOBS
     - TEST_NGINX_SLEEP=0.006
   matrix:
-    - NGINX_VERSION=1.9.15
-    - NGINX_VERSION=1.11.2
+    - NGINX_VERSION=1.27.1
 
 addons:
   apt:
@@ -43,7 +45,7 @@ cache:
   - download-cache
 
 install:
-  - git clone https://github.com/openresty/nginx-devel-utils.git
+  - git clone https://github.com/openresty/openresty-devel-utils.git
   - git clone https://github.com/openresty/openresty.git ../openresty
   - git clone https://github.com/openresty/no-pool-nginx.git ../no-pool-nginx
   - git clone https://github.com/simpl/ngx_devel_kit.git ../ndk-nginx-module
@@ -58,8 +60,8 @@ script:
   - make -j$JOBS CCDEBUG=-g Q= PREFIX=$LUAJIT_PREFIX CC=$CC XCFLAGS='-DLUA_USE_APICHECK -DLUA_USE_ASSERT' > build.log 2>&1 || (cat build.log && exit 1)
   - sudo make install PREFIX=$LUAJIT_PREFIX > build.log 2>&1 || (cat build.log && exit 1)
   - cd ../test-nginx && sudo cpanm . && cd ..
-  - export PATH=$PWD/work/nginx/sbin:$PWD/nginx-devel-utils:$PATH
+  - export PATH=$PWD/work/nginx/sbin:$PWD/openresty-devel-utils:$PATH
   - export NGX_BUILD_CC=$CC
   - sh util/build.sh $NGINX_VERSION > build.log 2>&1 || (cat build.log && exit 1)
   - nginx -V
-  - prove -r t
+  - prove -I. -r t
diff --git a/README.md b/README.md
index 443c5c3..d6c888c 100644
--- a/README.md
+++ b/README.md
@@ -263,23 +263,23 @@ You're recommended to install this module (as well as the Nginx core and many ot
 Alternatively, you can install this module manually with the Nginx source:
 
 Grab the nginx source code from [nginx.org](http://nginx.org/), for example,
-the version 1.9.7 (see [nginx compatibility](#compatibility)), and then build the source with this module:
+the version 1.13.6 (see [nginx compatibility](#compatibility)), and then build the source with this module:
 
 ```bash
+wget 'http://nginx.org/download/nginx-1.13.6.tar.gz'
+tar -xzvf nginx-1.13.6.tar.gz
+cd nginx-1.13.6/
 
- $ wget 'http://nginx.org/download/nginx-1.9.7.tar.gz'
- $ tar -xzvf nginx-1.9.7.tar.gz
- $ cd nginx-1.9.7/
+# Here we assume you would install you nginx under /opt/nginx/.
+./configure --prefix=/opt/nginx \
+  --add-module=/path/to/ngx_devel_kit \
+  --add-module=/path/to/array-var-nginx-module
 
- # Here we assume you would install you nginx under /opt/nginx/.
- $ ./configure --prefix=/opt/nginx \
-     --add-module=/path/to/array-var-nginx-module
-
- $ make -j2
- $ make install
+make -j2
+make install
 ```
 
-Download the latest version of the release tarball of this module from [array-var-nginx-module file list](https://github.com/openresty/array-var-nginx-module/tags).
+Download the latest version of the release tarball of this module from [array-var-nginx-module file list](https://github.com/openresty/array-var-nginx-module/tags), and the latest tarball for [ngx_devel_kit](https://github.com/simplresty/ngx_devel_kit) from its [file list](https://github.com/simplresty/ngx_devel_kit/tags).
 
 Also, this module is included and enabled by default in the [OpenResty bundle](http://openresty.org).
 
@@ -304,6 +304,10 @@ Compatibility
 
 The following versions of Nginx should work with this module:
 
+* **1.13.x** (last tested: 1.13.6)
+* **1.12.x**
+* **1.11.x** (last tested: 1.11.2)
+* **1.10.x**
 * **1.9.x** (last tested: 1.9.7)
 * **1.8.x**
 * **1.7.x** (last tested: 1.7.10)
diff --git a/src/ngx_http_array_var_module.c b/src/ngx_http_array_var_module.c
index 0b715b1..76c4df7 100644
--- a/src/ngx_http_array_var_module.c
+++ b/src/ngx_http_array_var_module.c
@@ -553,6 +553,9 @@ ngx_http_array_var_map(ngx_http_request_t *r, ngx_str_t *res,
     value = array->elts;
 
     array_it = ngx_http_get_indexed_variable(r, conf->array_it_index);
+    if (array_it == NULL) {
+        return NGX_ERROR;
+    }
 
     if (conf->in_place) {
         new_array = array;
diff --git a/valgrind.suppress b/valgrind.suppress
index ab1e4bb..50011ab 100644
--- a/valgrind.suppress
+++ b/valgrind.suppress
@@ -1,29 +1,29 @@
 {
-<insert_a_suppression_name_here>
-Memcheck:Param
-socketcall.sendmsg(msg.msg_iov[i])
-fun:sendmsg
-fun:ngx_write_channel
-fun:ngx_signal_worker_processes
-fun:ngx_master_process_cycle
-fun:main
+   <insert_a_suppression_name_here>
+   Memcheck:Param
+   socketcall.sendmsg(msg.msg_iov[i])
+   fun:sendmsg
+   fun:ngx_write_channel
+   fun:ngx_signal_worker_processes
+   fun:ngx_master_process_cycle
+   fun:main
 }
 {
-<insert_a_suppression_name_here>
-Memcheck:Addr4
-fun:ngx_init_cycle
-fun:ngx_master_process_cycle
-fun:main
+   <insert_a_suppression_name_here>
+   Memcheck:Addr4
+   fun:ngx_init_cycle
+   fun:ngx_master_process_cycle
+   fun:main
 }
 {
-<insert_a_suppression_name_here>
-Memcheck:Param
-socketcall.sendmsg(msg.msg_iov[i])
-fun:__sendmsg_nocancel
-fun:ngx_write_channel
-fun:ngx_signal_worker_processes
-fun:ngx_master_process_cycle
-fun:main
+   <insert_a_suppression_name_here>
+   Memcheck:Param
+   socketcall.sendmsg(msg.msg_iov[i])
+   fun:__sendmsg_nocancel
+   fun:ngx_write_channel
+   fun:ngx_signal_worker_processes
+   fun:ngx_master_process_cycle
+   fun:main
 }
 {
    <insert_a_suppression_name_here>
@@ -34,46 +34,39 @@ fun:main
 }
 {
    <insert_a_suppression_name_here>
-   Memcheck:Leak
-   fun:malloc
-   fun:ngx_alloc
-   fun:(below main)
-}
-{
-<insert_a_suppression_name_here>
-Memcheck:Param
-socketcall.sendmsg(msg.msg_iov[i])
-fun:__sendmsg_nocancel
-fun:ngx_write_channel
-fun:ngx_signal_worker_processes
-fun:ngx_master_process_cycle
-fun:main
+   Memcheck:Param
+   socketcall.sendmsg(msg.msg_iov[i])
+   fun:__sendmsg_nocancel
+   fun:ngx_write_channel
+   fun:ngx_signal_worker_processes
+   fun:ngx_master_process_cycle
+   fun:main
 }
 {
-<insert_a_suppression_name_here>
-Memcheck:Param
-socketcall.sendmsg(msg.msg_iov[i])
-fun:__sendmsg_nocancel
-fun:ngx_write_channel
-fun:ngx_master_process_cycle
-fun:main
+   <insert_a_suppression_name_here>
+   Memcheck:Param
+   socketcall.sendmsg(msg.msg_iov[i])
+   fun:__sendmsg_nocancel
+   fun:ngx_write_channel
+   fun:ngx_master_process_cycle
+   fun:main
 }
 {
-<insert_a_suppression_name_here>
-Memcheck:Param
-socketcall.sendmsg(msg.msg_iov[i])
-fun:__sendmsg_nocancel
-fun:ngx_write_channel
-fun:ngx_pass_open_channel
-fun:ngx_start_worker_processes
-fun:ngx_master_process_cycle
-fun:main
+   <insert_a_suppression_name_here>
+   Memcheck:Param
+   socketcall.sendmsg(msg.msg_iov[i])
+   fun:__sendmsg_nocancel
+   fun:ngx_write_channel
+   fun:ngx_pass_open_channel
+   fun:ngx_start_worker_processes
+   fun:ngx_master_process_cycle
+   fun:main
 }
 {
-<insert_a_suppression_name_here>
-Memcheck:Param
-epoll_ctl(event)
-fun:epoll_ctl
+   <insert_a_suppression_name_here>
+   Memcheck:Param
+   epoll_ctl(event)
+   fun:epoll_ctl
 }
 {
    nginx-core-process-init
@@ -157,3 +150,22 @@ fun:epoll_ctl
    fun:do_preload
    fun:dl_main
 }
+{
+   <insert_a_suppression_name_here>
+   Memcheck:Leak
+   match-leak-kinds: definite
+   fun:malloc
+   fun:ngx_alloc
+   fun:ngx_set_environment
+   fun:ngx_single_process_cycle
+}
+{
+   <insert_a_suppression_name_here>
+   Memcheck:Leak
+   match-leak-kinds: definite
+   fun:malloc
+   fun:ngx_alloc
+   fun:ngx_set_environment
+   fun:ngx_worker_process_init
+   fun:ngx_worker_process_cycle
+}