diff --git a/.travis.yml b/.travis.yml
index 0dcf5be4aa..71746a0ca2 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -35,6 +35,9 @@ matrix:
       env: PHPCS_BRANCH=2.9
     - php: nightly
       env: PHPCS_BRANCH=2.9
+    # Test PHP 5.3 with short_open_tags set to On (is Off by default)
+    - php: 5.3
+      env: PHPCS_BRANCH=master SHORT_OPEN_TAGS=true
   allow_failures:
     # Allow failures for unstable builds.
     - php: nightly
@@ -52,6 +55,7 @@ before_install:
     # test suite is currently not compatible with PHPUnit 6.x.
     # Fixed at a very specific PHPUnit version which is also compatible with HHVM.
     - if [[ ${TRAVIS_PHP_VERSION:0:2} != "5." ]]; then wget -P $PHPUNIT_DIR https://phar.phpunit.de/phpunit-5.7.17.phar && chmod +x $PHPUNIT_DIR/phpunit-5.7.17.phar; fi
+    - if [[ "$SHORT_OPEN_TAGS" == "true" ]]; then echo "short_open_tag = On" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini; fi
 
 script:
     # Lint the PHP files against parse errors.
diff --git a/WordPress/Sniffs/XSS/EscapeOutputSniff.php b/WordPress/Sniffs/XSS/EscapeOutputSniff.php
index 52e2396e11..c6f7625ce3 100644
--- a/WordPress/Sniffs/XSS/EscapeOutputSniff.php
+++ b/WordPress/Sniffs/XSS/EscapeOutputSniff.php
@@ -144,19 +144,42 @@ class WordPress_Sniffs_XSS_EscapeOutputSniff extends WordPress_Sniff {
 		'T_END_NOWDOC'               => true,
 	);
 
+	/**
+	 * Status of short_open_tag feature
+	 *
+	 * @since 0.11.0
+	 *
+	 * @var bool
+	 */
+	private $short_open_tag_enabled = true;
+
 	/**
 	 * Returns an array of tokens this test wants to listen for.
 	 *
 	 * @return array
 	 */
 	public function register() {
-		return array(
+		// Check whether short_open_tag is disabled on PHP version < 5.4 (it's enabled by default in later versions).
+		if ( PHP_VERSION_ID < 50400 && false === (bool) ini_get( 'short_open_tag' ) ) {
+			$this->short_open_tag_enabled = false;
+		}
+
+		$tokens = array(
 			T_ECHO,
 			T_PRINT,
 			T_EXIT,
 			T_STRING,
+			T_OPEN_TAG_WITH_ECHO,
 		);
 
+		/*
+		 * In case short_open_tag is turned off, we can attempt to regex T_INLINE_HTML
+		 * which is how short open tags are being handled in that case.
+		 */
+		if ( false === $this->short_open_tag_enabled ) {
+			$tokens[] = T_INLINE_HTML;
+		}
+		return $tokens;
 	}
 
 	/**
@@ -191,6 +214,24 @@ public function process_token( $stackPtr ) {
 			if ( in_array( $function, array( 'trigger_error', 'user_error' ), true ) ) {
 				$end_of_statement = $this->phpcsFile->findEndOfStatement( $open_paren + 1 );
 			}
+		} else if ( false === $this->short_open_tag_enabled && T_INLINE_HTML === $this->tokens[ $stackPtr ]['code'] ) {
+			// Skip if no PHP short_open_tag is in the string.
+			if ( false === strpos( $this->tokens[ $stackPtr ]['content'], '<?=' ) ) {
+				return;
+			}
+
+			// Report on what very likely is a PHP short open tag outputting variable.
+			if ( preg_match( '/\<\?\=[\s]*(\$[a-zA-Z_\x7f-\xff][a-zA-Z0-9_\x7f-\xff]*(?:(?:->\S+|\[[^\]]+\]))*)[\s]*;?[\s]*\?\>/', $this->tokens[ $stackPtr ]['content'], $matches ) ) {
+				$this->phpcsFile->addError( 'Expected next thing to be an escaping function, not %s.', $stackPtr, 'OutputNotEscaped', $matches[1] );
+				return;
+			}
+
+			// Throw warning in case the T_INLINE_HTML looks like a open_short_tag.
+			if ( false !== strpos( $this->tokens[ $stackPtr ]['content'], '<?=' ) ) {
+				$this->phpcsFile->addWarning( 'Possible use of PHP short open tag ( "<?=" ) detected. Needs manual inspection.', $stackPtr, 'PossibleShortOpenTag' );
+				return;
+			}
+			return;
 		}
 
 		// Checking for the ignore comment, ex: //xss ok.
diff --git a/WordPress/Tests/XSS/EscapeOutputUnitTest.inc b/WordPress/Tests/XSS/EscapeOutputUnitTest.inc
index 8c1f6a11cf..e00a1559b1 100644
--- a/WordPress/Tests/XSS/EscapeOutputUnitTest.inc
+++ b/WordPress/Tests/XSS/EscapeOutputUnitTest.inc
@@ -218,3 +218,10 @@ echo 1.234; // Ok.
 echo ( 1.234 + 10 + 2.5 ); // Ok.
 echo 10 % 2; // Ok.
 echo 8 * 1.2; // Ok.
+
+?>
+<?= $var ?><!-- Bad. -->
+<?= esc_html( $var ); ?><!-- Ok. -->
+<?= $var['foo']; ?><!-- Bad. -->
+<?= $var->foo ?><!-- Bad. -->
+<?php
diff --git a/WordPress/Tests/XSS/EscapeOutputUnitTest.php b/WordPress/Tests/XSS/EscapeOutputUnitTest.php
index 3eded37058..d3c7e5a8b4 100644
--- a/WordPress/Tests/XSS/EscapeOutputUnitTest.php
+++ b/WordPress/Tests/XSS/EscapeOutputUnitTest.php
@@ -64,6 +64,9 @@ public function getErrorList() {
 			206 => 1,
 			207 => 1,
 			212 => ( PHP_VERSION_ID < 50300 ) ? 1 : 0, // PHPCS on PHP 5.2 does not recognize T_NOWDOC.
+			210 => 1,
+			212 => 1,
+			213 => 1,
 		);
 
 	} // end getErrorList()
@@ -74,8 +77,14 @@ public function getErrorList() {
 	 * @return array <int line number> => <int number of warnings>
 	 */
 	public function getWarningList() {
-		return array();
+		$list = array();
 
+		// Adding Warning which is triggerred in case open_short_tag is set to Off.
+		if ( PHP_VERSION_ID < 50400 && false === (bool) ini_get( 'short_open_tag' ) ) {
+			$list[211] = 1;
+		}
+
+		return $list;
 	}
 
 } // End class.