diff --git a/src/Lint/PhpLint.php b/src/Lint/PhpLint.php
index ea15220..e8be861 100644
--- a/src/Lint/PhpLint.php
+++ b/src/Lint/PhpLint.php
@@ -50,7 +50,7 @@ public function getViolation(string $code): string
 
     private function ensureCodePrefix(string $code): string
     {
-        if (! preg_match('/<\?php/i', $code)) {
+        if (! preg_match('/<\?(=|php)/i', $code)) {
             return '<?php ' . PHP_EOL . $code;
         }
 
diff --git a/tests/assets/understand-short-tag.md b/tests/assets/understand-short-tag.md
new file mode 100644
index 0000000..4739289
--- /dev/null
+++ b/tests/assets/understand-short-tag.md
@@ -0,0 +1,3 @@
+```php
+<?= $this->json($this->data) ?>
+```
diff --git a/tests/assets/understand-short-tag.rst b/tests/assets/understand-short-tag.rst
new file mode 100644
index 0000000..cd8673b
--- /dev/null
+++ b/tests/assets/understand-short-tag.rst
@@ -0,0 +1,3 @@
+.. code-block:: php
+
+    <?= $this->json($this->data) ?>
diff --git a/tests/functional/md-short-php-tag.phpt b/tests/functional/md-short-php-tag.phpt
new file mode 100644
index 0000000..7c2c116
--- /dev/null
+++ b/tests/functional/md-short-php-tag.phpt
@@ -0,0 +1,14 @@
+--TEST--
+Report a warning in case of missing PHP open tag
+--FILE--
+<?php
+
+$checkRunner = require __DIR__ . '/init.php';
+
+$checkRunner('tests/assets/understand-short-tag.md');
+
+--EXPECTF--
+Finding documentation files on tests/assets/understand-short-tag.md
+
+
+     Everything is OK!
diff --git a/tests/functional/rst-short-php-tag.phpt b/tests/functional/rst-short-php-tag.phpt
new file mode 100644
index 0000000..00baed7
--- /dev/null
+++ b/tests/functional/rst-short-php-tag.phpt
@@ -0,0 +1,14 @@
+--TEST--
+Report a warning in case of missing PHP open tag
+--FILE--
+<?php
+
+$checkRunner = require __DIR__ . '/init.php';
+
+$checkRunner('tests/assets/understand-short-tag.rst');
+
+--EXPECTF--
+Finding documentation files on tests/assets/understand-short-tag.rst
+
+
+     Everything is OK!