diff --git a/.travis.yml b/.travis.yml
index 13e1961..3077c26 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,16 +1,17 @@
 # .travis.yml
 
 language: php
+dist: bionic
 php:
-  - 5.3
-  - 5.4
-  - 5.5
-  - 5.6
+  - 7.2
+  - 7.3
+  - 7.4
+  - 8.0
 
 # Install dependencies before testing
 before_script:
   - composer selfupdate
-  - composer install --dev
+  - composer install
 
 # Use our custom version of phpunit
 script:
@@ -19,4 +20,4 @@ script:
 
 # Run coveralls.io code coverage report
 after_script:
-  - vendor/bin/coveralls -v
\ No newline at end of file
+  - vendor/bin/php-coveralls -v
diff --git a/composer.json b/composer.json
index 1c30ca7..b728310 100644
--- a/composer.json
+++ b/composer.json
@@ -10,12 +10,15 @@
     }
   ],
   "require": {
-    "php": ">=5.3.0"
+    "php": ">=7.2"
+  },
+  "conflict": {
+    "monolog/monolog": "<2.0"
   },
   "require-dev": {
-    "monolog/monolog": "~1.0",
-    "phpunit/phpunit": "~4.0",
-    "satooshi/php-coveralls": "dev-master"
+    "monolog/monolog": "^2.0",
+    "phpunit/phpunit": "^8.5",
+    "php-coveralls/php-coveralls": "^2.4"
   },
   "autoload": {
     "psr-4": {
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index d4b5eaa..6788e45 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -8,7 +8,7 @@
 
     <testsuites>
         <testsuite name="monolog-splunk-formatter Unit Tests">
-            <directory phpVersion="5.3.0" phpVersionOperator=">=">test/unit</directory>
+            <directory>test</directory>
         </testsuite>
     </testsuites>
 
@@ -19,8 +19,8 @@
     </filter>
 
     <logging>
-        <log type="coverage-html" target="build/coverage" charset="UTF-8" highlight="true" lowUpperBound="50" highUpperBound="90"/>
+        <log type="coverage-html" target="build/coverage" lowUpperBound="50" highLowerBound="90"/>
         <log type="coverage-clover" target="build/logs/clover.xml"/>
     </logging>
 
-</phpunit>
\ No newline at end of file
+</phpunit>
diff --git a/src/SplunkLineFormatter.php b/src/SplunkLineFormatter.php
index 45c68ce..f1983d2 100644
--- a/src/SplunkLineFormatter.php
+++ b/src/SplunkLineFormatter.php
@@ -1,4 +1,5 @@
-<?php
+<?php declare(strict_types=1);
+
 /*
  * @copyright 2015 Vubeology, Inc.
  * @license MIT
@@ -15,18 +16,18 @@
  */
 class SplunkLineFormatter extends LineFormatter
 {
-    const SPLUNK_FORMAT = "%datetime% %channel%.%level_name% L=%level% %message% %context% %extra%\n";
+    public const SPLUNK_FORMAT = "%datetime% %channel%.%level_name% L=%level% %message% %context% %extra%\n";
 
     protected $quoteReplacement;
 
     /**
-     * @param string $format                     The format of the message
-     * @param string $dateFormat                 The format of the timestamp: one supported by DateTime::format
-     * @param bool   $allowInlineLineBreaks      Whether to allow inline line breaks in log entries
-     * @param bool   $ignoreEmptyContextAndExtra
+     * @param string|null $format                     The format of the message
+     * @param string|null $dateFormat                 The format of the timestamp: one supported by DateTime::format
+     * @param bool        $allowInlineLineBreaks      Whether to allow inline line breaks in log entries
+     * @param bool        $ignoreEmptyContextAndExtra
+     * @param string      $quoteReplacement
      */
-    public function __construct($format = null, $dateFormat = null, $allowInlineLineBreaks = false, $ignoreEmptyContextAndExtra = false,
-    $quoteReplacement = '^')
+    public function __construct(?string $format = null, ?string $dateFormat = null, bool $allowInlineLineBreaks = false, bool $ignoreEmptyContextAndExtra = false, string $quoteReplacement = '^')
     {
         if($format === null) {
             $format = self::SPLUNK_FORMAT;
@@ -40,29 +41,25 @@ public function __construct($format = null, $dateFormat = null, $allowInlineLine
         parent::__construct($format, $dateFormat, $allowInlineLineBreaks, $ignoreEmptyContextAndExtra);
     }
 
-    public function setQuoteReplacement($quoteReplacement)
+    public function setQuoteReplacement($quoteReplacement): void
     {
         $this->quoteReplacement = $quoteReplacement;
     }
 
-    protected function jsonEncode($data)
+    protected function jsonEncode($data): string
     {
-        if (version_compare(PHP_VERSION, '5.4.0', '>=')) {
-            return $this->toJson($data, true);
-        }
-
-        return str_replace('\\/', '/', @json_encode($data));
+        return $this->toJson($data, true);
     }
 
     /**
      * Public so we can run unit tests against it
      */
-    public function publicConvertToString($data)
+    public function publicConvertToString($data): string
     {
         return $this->convertToString($data);
     }
 
-    protected function convertToString($data)
+    protected function convertToString($data): string
     {
         if (null === $data || is_bool($data)) {
             return var_export($data, true);
@@ -74,7 +71,7 @@ protected function convertToString($data)
 
         if (is_array($data)) {
 
-            $vals = array();
+            $vals = [];
 
             foreach ($data as $n => $v) {
                 if (null === $v || is_bool($v)) {
@@ -103,9 +100,9 @@ protected function convertToString($data)
         return $this->jsonEncode($data);
     }
 
-    protected function toQuoteSafeString($string)
+    protected function toQuoteSafeString($string): string
     {
         return str_replace('"', $this->quoteReplacement, (string) $string);
     }
 
-}
\ No newline at end of file
+}
diff --git a/test/unit/SplunkLinkFormatterTest.php b/test/SplunkLineFormatterTest.php
similarity index 94%
rename from test/unit/SplunkLinkFormatterTest.php
rename to test/SplunkLineFormatterTest.php
index 9b86c26..b3d0bf6 100644
--- a/test/unit/SplunkLinkFormatterTest.php
+++ b/test/SplunkLineFormatterTest.php
@@ -1,17 +1,17 @@
 <?php
 
+use PHPUnit\Framework\TestCase;
 use \Vube\Monolog\Formatter\SplunkLineFormatter;
 use \Monolog\Logger;
 use \Monolog\Handler\TestHandler;
 
-
-class SplunkLineFormatterTest extends \PHPUnit_Framework_TestCase
+class SplunkLineFormatterTest extends TestCase
 {
     private $log;
     private $handler;
     private $slf;
 
-    protected function setUp()
+    protected function setUp(): void
     {
         $this->slf = new SplunkLineFormatter();
 
@@ -153,7 +153,7 @@ public function testLogFormat()
         $context = array(
             'a' => 'A A',
         );
-        $this->log->addNotice('message here', $context);
+        $this->log->notice('message here', $context);
         $records = $this->handler->getRecords();
         $this->assertSame(1, count($records));
         $message = $records[0]['formatted'];
@@ -166,7 +166,7 @@ public function testLogFormatWithQuotesInMessage()
         $context = array(
             'a' => 'A A',
         );
-        $this->log->addWarning('message "with quotes"', $context);
+        $this->log->warning('message "with quotes"', $context);
         $records = $this->handler->getRecords();
         $this->assertSame(1, count($records));
         $message = $records[0]['formatted'];
@@ -181,7 +181,7 @@ public function testLogWithAssocArrayInContext()
                 'ca' => 'CA',
             ),
         );
-        $this->log->addWarning('message', $context);
+        $this->log->warning('message', $context);
         $records = $this->handler->getRecords();
         $this->assertSame(1, count($records));
         $message = $records[0]['formatted'];