diff --git a/lib/resty/healthcheck.lua b/lib/resty/healthcheck.lua
index 8b3bd47b..53b38588 100644
--- a/lib/resty/healthcheck.lua
+++ b/lib/resty/healthcheck.lua
@@ -24,6 +24,7 @@
 -- @author Hisham Muhammad, Thijs Schreijer
 -- @license Apache 2.0
 
+local ngx = ngx
 local ERR = ngx.ERR
 local WARN = ngx.WARN
 local DEBUG = ngx.DEBUG
@@ -38,6 +39,17 @@ local resty_lock = require ("resty.lock")
 local re_find = ngx.re.find
 local bit = require("bit")
 local ngx_now = ngx.now
+local error = error
+local print = print
+local require = require
+local string = string
+local assert = assert
+local tonumber = tonumber
+local type = type
+local math = math
+local next = next
+local pairs = pairs
+local table = table
 
 -- constants
 local EVENT_SOURCE_PREFIX = "lua-resty-healthcheck"
@@ -503,8 +515,8 @@ local function incr_counter(self, health_report, ip, port, hostname, limit, ctr_
     local ctr = ctr_get(multictr, ctr_type)
 
     self:log(WARN, health_report, " ", COUNTER_NAMES[ctr_type],
-                   " increment (", ctr, "/", limit, ") for '", hostname or "",
-                   "(", ip, ":", port, ")'")
+             " increment (", ctr, "/", limit, ") for '", hostname or "",
+             "(", ip, ":", port, ")'")
 
     local new_multictr
     if ctr_type == CTR_SUCCESS then
@@ -1011,7 +1023,7 @@ end
 -- Log a message specific to this checker
 -- @param level standard ngx log level constant
 function checker:log(level, ...)
-  ngx_log(level, worker_color(self.LOG_PREFIX), ...)
+  return ngx_log(level, worker_color(self.LOG_PREFIX), ...)
 end
 
 
diff --git a/lib/resty/healthcheck/utils.lua b/lib/resty/healthcheck/utils.lua
index b95731e7..8faa6c80 100644
--- a/lib/resty/healthcheck/utils.lua
+++ b/lib/resty/healthcheck/utils.lua
@@ -6,6 +6,9 @@
 -- @author Hisham Muhammad, Thijs Schreijer
 -- @license Apache 2.0
 
+local assert = assert
+local type = type
+
 local timer_at = ngx.timer.at
 
 local _M = {}
diff --git a/t/00-new.t b/t/00-new.t
index d8d11c6b..a3945b72 100644
--- a/t/00-new.t
+++ b/t/00-new.t
@@ -34,6 +34,8 @@ GET /t
 --- error_log
 please configure
 
+
+
 === TEST 2: new() requires 'name'
 --- http_config eval: $::HttpConfig
 --- config
@@ -55,6 +57,8 @@ GET /t
 --- error_log
 required option 'name' is missing
 
+
+
 === TEST 3: new() requires 'shm_name'
 --- http_config eval: $::HttpConfig
 --- config
@@ -76,6 +80,8 @@ GET /t
 --- error_log
 required option 'shm_name' is missing
 
+
+
 === TEST 4: new() fails with invalid shm
 --- http_config eval: $::HttpConfig
 --- config
@@ -98,6 +104,8 @@ GET /t
 --- error_log
 no shm found by name
 
+
+
 === TEST 5: new() initializes with default config
 --- http_config eval: $::HttpConfig
 --- config
@@ -119,6 +127,8 @@ GET /t
 --- error_log
 Healthchecker started!
 
+
+
 === TEST 6: new() only accepts http or tcp types
 --- http_config eval: $::HttpConfig
 --- config
@@ -154,6 +164,8 @@ true
 true
 false
 
+
+
 === TEST 7: new() deals with bad inputs
 --- http_config eval: $::HttpConfig
 --- config
diff --git a/t/01-start-stop.t b/t/01-start-stop.t
index a3e189e3..e460562c 100644
--- a/t/01-start-stop.t
+++ b/t/01-start-stop.t
@@ -54,6 +54,8 @@ true
 --- no_error_log
 [error]
 
+
+
 === TEST 2: start() cannot start a second time using active health checks
 --- http_config eval: $::HttpConfig
 --- config
@@ -87,6 +89,8 @@ cannot start, 2 (of 2) timers are still running
 --- no_error_log
 [error]
 
+
+
 === TEST 3: start() is a no-op if active intervals are 0
 --- http_config eval: $::HttpConfig
 --- config
@@ -128,6 +132,8 @@ true
 --- no_error_log
 [error]
 
+
+
 === TEST 4: stop() stops health checks
 --- http_config eval: $::HttpConfig
 --- config
@@ -167,6 +173,8 @@ true
 [error]
 checking
 
+
+
 === TEST 5: start() restarts health checks
 --- http_config eval: $::HttpConfig
 --- config
diff --git a/t/04-report_success.t b/t/04-report_success.t
index 91b36a10..628ad2d4 100644
--- a/t/04-report_success.t
+++ b/t/04-report_success.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: report_success() recovers HTTP active + passive
 --- http_config eval
 qq{
@@ -96,6 +94,7 @@ healthy SUCCESS increment (3/3) for '(127.0.0.1:2116)'
 event: target status '(127.0.0.1:2118)' from 'false' to 'true'
 
 
+
 === TEST 2: report_success() recovers TCP active = passive
 --- http_config eval
 qq{
@@ -172,6 +171,8 @@ healthy SUCCESS increment (2/3) for '(127.0.0.1:2116)'
 healthy SUCCESS increment (3/3) for '(127.0.0.1:2116)'
 event: target status '(127.0.0.1:2118)' from 'false' to 'true'
 
+
+
 === TEST 3: report_success() is a nop when active.healthy.sucesses == 0
 --- http_config eval
 qq{
diff --git a/t/05-report_failure.t b/t/05-report_failure.t
index 9b95c395..714e7248 100644
--- a/t/05-report_failure.t
+++ b/t/05-report_failure.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: report_failure() fails HTTP active + passive
 --- http_config eval
 qq{
@@ -96,6 +94,7 @@ unhealthy HTTP increment (3/3) for '(127.0.0.1:2113)'
 event: target status '(127.0.0.1:2113)' from 'true' to 'false'
 
 
+
 === TEST 2: report_failure() fails TCP active + passive
 --- http_config eval
 qq{
@@ -171,6 +170,7 @@ unhealthy TCP increment (2/2) for '(127.0.0.1:2113)'
 event: target status '(127.0.0.1:2113)' from 'true' to 'false'
 
 
+
 === TEST 3: report_failure() is a nop when failure counters == 0
 --- http_config eval
 qq{
diff --git a/t/06-report_http_status.t b/t/06-report_http_status.t
index f70bc0a0..013d70dc 100644
--- a/t/06-report_http_status.t
+++ b/t/06-report_http_status.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: report_http_status() failures active + passive
 --- http_config eval
 qq{
@@ -178,6 +176,7 @@ healthy SUCCESS increment (4/4) for '(127.0.0.1:2113)'
 event: target status '(127.0.0.1:2113)' from 'false' to 'true'
 
 
+
 === TEST 3: report_http_status() with success is a nop when passive.healthy.successes == 0
 --- http_config eval
 qq{
@@ -245,6 +244,7 @@ healthy SUCCESS increment
 event: target status '127.0.0.1 (127.0.0.1:2119)' from 'false' to 'true'
 
 
+
 === TEST 4: report_http_status() with success is a nop when active.healthy.successes == 0
 --- http_config eval
 qq{
@@ -312,6 +312,7 @@ healthy SUCCESS increment
 event: target status '127.0.0.1 (127.0.0.1:2119)' from 'false' to 'true'
 
 
+
 === TEST 5: report_http_status() with failure is a nop when passive.unhealthy.http_failures == 0
 --- http_config eval
 qq{
@@ -379,7 +380,8 @@ unhealthy HTTP increment
 event: target status '127.0.0.1 (127.0.0.1:2119)' from 'true' to 'false'
 
 
-=== TEST 4: report_http_status() with success is a nop when active.unhealthy.http_failures == 0
+
+=== TEST 6: report_http_status() with success is a nop when active.unhealthy.http_failures == 0
 --- http_config eval
 qq{
     $::HttpConfig
diff --git a/t/07-report_tcp_failure.t b/t/07-report_tcp_failure.t
index f0d8b6b4..5baa983f 100644
--- a/t/07-report_tcp_failure.t
+++ b/t/07-report_tcp_failure.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: report_tcp_failure() active + passive
 --- http_config eval
 qq{
@@ -96,6 +94,7 @@ unhealthy TCP increment (3/3) for '(127.0.0.1:2113)'
 event: target status '(127.0.0.1:2113)' from 'true' to 'false'
 
 
+
 === TEST 2: report_tcp_failure() for active is a nop when active.unhealthy.tcp_failures == 0
 --- http_config eval
 qq{
diff --git a/t/08-report_timeout.t b/t/08-report_timeout.t
index 7f4ef911..b8658e4f 100644
--- a/t/08-report_timeout.t
+++ b/t/08-report_timeout.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: report_timeout() active + passive
 --- http_config eval
 qq{
@@ -94,6 +92,7 @@ unhealthy TIMEOUT increment (2/2) for '(127.0.0.1:2113)'
 event: target status '(127.0.0.1:2113)' from 'true' to 'false'
 
 
+
 === TEST 2: report_timeout() for active is a nop when active.unhealthy.timeouts == 0
 --- http_config eval
 qq{
diff --git a/t/09-active_probes.t b/t/09-active_probes.t
index fa1bdce8..9f1e83f0 100644
--- a/t/09-active_probes.t
+++ b/t/09-active_probes.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: active probes, http node failing
 --- http_config eval
 qq{
@@ -127,6 +125,8 @@ healthy SUCCESS increment (3/3) for '(127.0.0.1:2114)'
 event: target status '(127.0.0.1:2114)' from 'false' to 'true'
 checking unhealthy targets: nothing to do
 
+
+
 === TEST 3: active probes, custom http status (regression test for pre-filled defaults)
 --- http_config eval
 qq{
@@ -183,6 +183,7 @@ unhealthy HTTP increment (3/3) for '(127.0.0.1:2114)'
 event: target status '(127.0.0.1:2114)' from 'true' to 'false'
 
 
+
 === TEST 4: active probes, custom http status, node failing
 --- http_config eval
 qq{
@@ -295,6 +296,7 @@ event: target status 'example.com(127.0.0.1:2114)' from 'false' to 'true'
 checking unhealthy targets: nothing to do
 
 
+
 === TEST 6: active probes, tcp node failing
 --- http_config eval
 qq{
@@ -395,4 +397,3 @@ healthy SUCCESS increment (2/3) for '(127.0.0.1:2114)'
 healthy SUCCESS increment (3/3) for '(127.0.0.1:2114)'
 event: target status '(127.0.0.1:2114)' from 'false' to 'true'
 checking unhealthy targets: nothing to do
-
diff --git a/t/10-garbagecollect.t b/t/10-garbagecollect.t
index e38ec55a..210cfcac 100644
--- a/t/10-garbagecollect.t
+++ b/t/10-garbagecollect.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: garbage collect the checker object
 --- http_config eval
 qq{
diff --git a/t/11-clear.t b/t/11-clear.t
index 70f1407f..3473f9b3 100644
--- a/t/11-clear.t
+++ b/t/11-clear.t
@@ -72,6 +72,8 @@ initial target list (9 targets)
 initial target list (10 targets)
 initial target list (11 targets)
 
+
+
 === TEST 2: clear() clears the list, other checkers get notified and clear too
 --- http_config eval: $::HttpConfig
 --- config
@@ -115,6 +117,8 @@ checking unhealthy targets: nothing to do
 --- no_error_log
 checking unhealthy targets: #10
 
+
+
 === TEST 3: clear() resets counters
 --- http_config eval
 qq{
diff --git a/t/12-set_target_status.t b/t/12-set_target_status.t
index ff69adc0..fe8aa10a 100644
--- a/t/12-set_target_status.t
+++ b/t/12-set_target_status.t
@@ -47,6 +47,9 @@ GET /t
 true
 false
 true
+
+
+
 === TEST 2: set_target_status() restores node after passive check disables it
 --- http_config eval
 qq{
@@ -86,6 +89,9 @@ GET /t
 true
 false
 true
+
+
+
 === TEST 3: set_target_status() resets the failure counters
 --- http_config eval
 qq{
@@ -129,7 +135,10 @@ GET /t
 true
 true
 false
-=== TEST 3: set_target_status() resets the success counters
+
+
+
+=== TEST 4: set_target_status() resets the success counters
 --- http_config eval
 qq{
     $::HttpConfig
diff --git a/t/13-integration.t b/t/13-integration.t
index bc3549f3..43b08b1c 100644
--- a/t/13-integration.t
+++ b/t/13-integration.t
@@ -17,8 +17,6 @@ run_tests();
 
 __DATA__
 
-
-
 === TEST 1: ensure counters work properly
 --- http_config eval
 qq{
diff --git a/t/14-tls_active_probes.t b/t/14-tls_active_probes.t
index 51854928..e5957a29 100644
--- a/t/14-tls_active_probes.t
+++ b/t/14-tls_active_probes.t
@@ -6,24 +6,28 @@ workers(1);
 plan tests => blocks() * 2;
 
 my $pwd = cwd();
+my $ca_certs = '/etc/ssl/certs/ca-certificates.crt';
+if (!-e $ca_certs) {
+    # for centos or redhat
+    $ca_certs = '/etc/ssl/certs/ca-bundle.trust.crt';
+}
 
 our $HttpConfig = qq{
     lua_package_path "$pwd/lib/?.lua;;";
     lua_shared_dict test_shm 8m;
     lua_shared_dict my_worker_events 8m;
+
+    lua_ssl_trusted_certificate $ca_certs;
 };
 
 run_tests();
 
 __DATA__
 
-
-
 === TEST 1: active probes, valid https
 --- http_config eval: $::HttpConfig
 --- config
     location = /t {
-        lua_ssl_trusted_certificate /etc/ssl/certs/ca-certificates.crt;
         lua_ssl_verify_depth 2;
         content_by_lua_block {
             local we = require "resty.worker.events"
@@ -59,11 +63,12 @@ true
 --- timeout
 15
 
+
+
 === TEST 2: active probes, invalid cert
 --- http_config eval: $::HttpConfig
 --- config
     location = /t {
-        lua_ssl_trusted_certificate /etc/ssl/certs/ca-certificates.crt;
         lua_ssl_verify_depth 2;
         content_by_lua_block {
             local we = require "resty.worker.events"
@@ -99,11 +104,12 @@ false
 --- timeout
 15
 
+
+
 === TEST 3: active probes, accept invalid cert when disabling check
 --- http_config eval: $::HttpConfig
 --- config
     location = /t {
-        lua_ssl_trusted_certificate /etc/ssl/certs/ca-certificates.crt;
         lua_ssl_verify_depth 2;
         content_by_lua_block {
             local we = require "resty.worker.events"