diff --git a/.phpcs.xml b/.phpcs.xml
new file mode 100644
index 0000000..210d7c4
--- /dev/null
+++ b/.phpcs.xml
@@ -0,0 +1,32 @@
+<?xml version="1.0"?>
+<ruleset name="cebe/markdown">
+    <rule ref="PSR2">
+        <exclude name="Generic.WhiteSpace.DisallowTabIndent" />
+
+        <!-- @TODO The following exclusions need to be checked for validity. -->
+        <exclude name="Squiz.ControlStructures.ControlSignature.SpaceAfterKeyword" />
+        <exclude name="Generic.Files.LineLength.TooLong" />
+        <exclude name="Squiz.WhiteSpace.SuperfluousWhitespace.EndLine" />
+        <exclude name="PSR2.Classes.ClassDeclaration.CloseBraceAfterBody" />
+        <exclude name="PSR2.Files.EndFileNewline.NoneFound" />
+        <exclude name="PSR1.Classes.ClassDeclaration.MultipleClasses" />
+        <exclude name="PSR2.Classes.ClassDeclaration.SpaceBeforeName" />
+        <exclude name="PSR2.Namespaces.NamespaceDeclaration.BlankLineAfter" />
+        <exclude name="Squiz.WhiteSpace.ControlStructureSpacing.SpacingAfterOpen" />
+        <exclude name="Squiz.ControlStructures.ControlSignature.SpaceAfterCloseParenthesis" />
+        <exclude name="PSR2.Classes.PropertyDeclaration.Underscore" />
+        <exclude name="Squiz.Functions.MultiLineFunctionDeclaration.SpaceAfterFunction" />
+        <exclude name="PSR2.Classes.PropertyDeclaration.Underscore" />
+
+    </rule>
+    <rule ref="Generic.WhiteSpace.DisallowSpaceIndent" />
+    <arg name="tab-width" value="4" />
+    <rule ref="Generic.WhiteSpace.ScopeIndent">
+        <properties>
+            <property name="indent" value="4"/>
+            <property name="tabIndent" value="true"/>
+        </properties>
+    </rule>
+    <file>.</file>
+    <exclude-pattern>vendor/</exclude-pattern>
+</ruleset>
diff --git a/.travis.yml b/.travis.yml
index b2f0324..3ea0161 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -34,6 +34,7 @@ install:
   - composer install --prefer-dist
 
 script:
+  - vendor/bin/phpcs -s
   - vendor/bin/phpunit --verbose --coverage-clover=coverage.clover
 # test against standard markdown spec
 #  - git clone https://github.com/jgm/stmd && cd stmd && perl runtests.pl spec.txt ../bin/markdown
diff --git a/block/CodeTrait.php b/block/CodeTrait.php
index 2457ece..b970065 100644
--- a/block/CodeTrait.php
+++ b/block/CodeTrait.php
@@ -38,7 +38,7 @@ protected function consumeCode($lines, $current)
 				$content[] = $line;
 			// but also if it is empty and the next line is intended by 4 spaces or a tab
 			} elseif (($line === '' || rtrim($line) === '') && isset($lines[$i + 1][0]) &&
-				      ($lines[$i + 1][0] === "\t" || strncmp($lines[$i + 1], '    ', 4) === 0)) {
+					($lines[$i + 1][0] === "\t" || strncmp($lines[$i + 1], '    ', 4) === 0)) {
 				if ($line !== '') {
 					$line = $line[0] === "\t" ? substr($line, 1) : substr($line, 4);
 				}
diff --git a/block/ListTrait.php b/block/ListTrait.php
index 7e53a76..52e438e 100644
--- a/block/ListTrait.php
+++ b/block/ListTrait.php
@@ -34,7 +34,7 @@ protected function identifyUl($line)
 	{
 		$l = $line[0];
 		return ($l === '-' || $l === '+' || $l === '*') && (isset($line[1]) && (($l1 = $line[1]) === ' ' || $l1 === "\t")) ||
-		       ($l === ' ' && preg_match('/^ {0,3}[\-\+\*][ \t]/', $line));
+			($l === ' ' && preg_match('/^ {0,3}[\-\+\*][ \t]/', $line));
 	}
 
 	/**
diff --git a/composer.json b/composer.json
index 6a3160e..cd37742 100644
--- a/composer.json
+++ b/composer.json
@@ -24,7 +24,8 @@
 	"require-dev": {
 		"phpunit/phpunit": "4.1.*",
 		"facebook/xhprof": "*@dev",
-		"cebe/indent": "*"
+		"cebe/indent": "*",
+		"squizlabs/php_codesniffer": "^3.6"
 	},
 	"autoload": {
 		"psr-4": {
diff --git a/inline/EmphStrongTrait.php b/inline/EmphStrongTrait.php
index ca91929..a8cc374 100644
--- a/inline/EmphStrongTrait.php
+++ b/inline/EmphStrongTrait.php
@@ -82,6 +82,6 @@ protected function renderEmph($block)
 		return '<em>' . $this->renderAbsy($block[1]) . '</em>';
 	}
 
-    abstract protected function parseInline($text);
-    abstract protected function renderAbsy($blocks);
+	abstract protected function parseInline($text);
+	abstract protected function renderAbsy($blocks);
 }
diff --git a/inline/StrikeoutTrait.php b/inline/StrikeoutTrait.php
index 0e1d21a..c350c7b 100644
--- a/inline/StrikeoutTrait.php
+++ b/inline/StrikeoutTrait.php
@@ -35,6 +35,6 @@ protected function renderStrike($block)
 		return '<del>' . $this->renderAbsy($block[1]) . '</del>';
 	}
 
-    abstract protected function parseInline($text);
-    abstract protected function renderAbsy($blocks);
+	abstract protected function parseInline($text);
+	abstract protected function renderAbsy($blocks);
 }