diff --git a/phpBB/phpbb/textformatter/s9e/factory.php b/phpBB/phpbb/textformatter/s9e/factory.php
index 4a04b34cd8..63b23d2fd0 100644
--- a/phpBB/phpbb/textformatter/s9e/factory.php
+++ b/phpBB/phpbb/textformatter/s9e/factory.php
@@ -104,7 +104,7 @@ class factory implements \phpbb\textformatter\cache_interface
 		'b'     => '<span style="font-weight: bold"><xsl:apply-templates/></span>',
 		'i'     => '<span style="font-style: italic"><xsl:apply-templates/></span>',
 		'u'     => '<span style="text-decoration: underline"><xsl:apply-templates/></span>',
-		'img'   => '<img src="{IMAGEURL}" alt="{L_IMAGE}"/>',
+		'img'   => '<img src="{IMAGEURL}" class="postimage" alt="{L_IMAGE}"/>',
 		'size'  => '<span style="font-size: {FONTSIZE}%; line-height: normal"><xsl:apply-templates/></span>',
 		'color' => '<span style="color: {COLOR}"><xsl:apply-templates/></span>',
 		'email' => '<a>
diff --git a/tests/text_formatter/s9e/default_formatting_test.php b/tests/text_formatter/s9e/default_formatting_test.php
index 390bc65264..3047653d51 100644
--- a/tests/text_formatter/s9e/default_formatting_test.php
+++ b/tests/text_formatter/s9e/default_formatting_test.php
@@ -132,7 +132,7 @@ class phpbb_textformatter_s9e_default_formatting_test extends phpbb_test_case
 			),
 			array(
 				'[img]https://area51.phpbb.com/images/area51.png[/img]',
-				'<img src="https://area51.phpbb.com/images/area51.png" alt="Image">'
+				'<img src="https://area51.phpbb.com/images/area51.png" class="postimage" alt="Image">'
 			),
 			array(
 				'[url]https://area51.phpbb.com/[/url]',
diff --git a/tests/text_formatter/s9e/fixtures/styles/bar/template/bbcode.html b/tests/text_formatter/s9e/fixtures/styles/bar/template/bbcode.html
index a17446581a..76a35542be 100644
--- a/tests/text_formatter/s9e/fixtures/styles/bar/template/bbcode.html
+++ b/tests/text_formatter/s9e/fixtures/styles/bar/template/bbcode.html
@@ -31,7 +31,7 @@
 
 <!-- BEGIN size --><span style="font-size: {SIZE}%; line-height: 116%;">{TEXT}</span><!-- END size -->
 
-<!-- BEGIN img --><img src="{URL}" alt="{L_IMAGE}" /><!-- END img -->
+<!-- BEGIN img --><img src="{URL}" class="postimage" alt="{L_IMAGE}" /><!-- END img -->
 
 <!-- BEGIN url --><a href="{URL}" class="postlink">{DESCRIPTION}</a><!-- END url -->
 
diff --git a/tests/text_formatter/s9e/fixtures/styles/barplus/template/bbcode.html b/tests/text_formatter/s9e/fixtures/styles/barplus/template/bbcode.html
index cd2f0acae3..fad8d828fd 100644
--- a/tests/text_formatter/s9e/fixtures/styles/barplus/template/bbcode.html
+++ b/tests/text_formatter/s9e/fixtures/styles/barplus/template/bbcode.html
@@ -31,7 +31,7 @@
 
 <!-- BEGIN size --><span style="font-size: {SIZE}%; line-height: 116%;">{TEXT}</span><!-- END size -->
 
-<!-- BEGIN img --><img src="{URL}" alt="{L_IMAGE}" /><!-- END img -->
+<!-- BEGIN img --><img src="{URL}" class="postimage" alt="{L_IMAGE}" /><!-- END img -->
 
 <!-- BEGIN url --><a href="{URL}" class="postlink">{DESCRIPTION}</a><!-- END url -->
 
diff --git a/tests/text_formatter/s9e/fixtures/styles/foo/template/bbcode.html b/tests/text_formatter/s9e/fixtures/styles/foo/template/bbcode.html
index 909c09df5a..3e38d13a32 100644
--- a/tests/text_formatter/s9e/fixtures/styles/foo/template/bbcode.html
+++ b/tests/text_formatter/s9e/fixtures/styles/foo/template/bbcode.html
@@ -31,7 +31,7 @@
 
 <!-- BEGIN size --><span style="font-size: {SIZE}%; line-height: 116%;">{TEXT}</span><!-- END size -->
 
-<!-- BEGIN img --><img src="{URL}" alt="{L_IMAGE}" /><!-- END img -->
+<!-- BEGIN img --><img src="{URL}" class="postimage" alt="{L_IMAGE}" /><!-- END img -->
 
 <!-- BEGIN url --><a href="{URL}" class="postlink">{DESCRIPTION}</a><!-- END url -->
 
diff --git a/tests/text_formatter/s9e/renderer_test.php b/tests/text_formatter/s9e/renderer_test.php
index 3c0bbb96c7..ad5bfa78fc 100644
--- a/tests/text_formatter/s9e/renderer_test.php
+++ b/tests/text_formatter/s9e/renderer_test.php
@@ -112,7 +112,7 @@ class phpbb_textformatter_s9e_renderer_test extends phpbb_test_case
 			),
 			array(
 				'<r><IMG src="http://example.org/foo.png"><s>[img]</s>http://example.org/foo.png<e>[/img]</e></IMG></r>',
-				'<img src="http://example.org/foo.png" alt="Image">',
+				'<img src="http://example.org/foo.png" class="postimage" alt="Image">',
 				array('set_viewimg' => true)
 			),
 			array(
@@ -231,7 +231,7 @@ class phpbb_textformatter_s9e_renderer_test extends phpbb_test_case
 			),
 			array(
 				'<r><IMG src="http://localhost/mrgreen.gif"><s>[img]</s><URL url="http://localhost/mrgreen.gif">http://localhost/mrgreen.gif</URL><e>[/img]</e></IMG></r>',
-				'<img src="http://localhost/mrgreen.gif" alt="Image">'
+				'<img src="http://localhost/mrgreen.gif" class="postimage" alt="Image">'
 			),
 			array(
 				'<r><IMG src="http://localhost/mrgreen.gif"><s>[img]</s><URL url="http://localhost/mrgreen.gif">http://localhost/mrgreen.gif</URL><e>[/img]</e></IMG></r>',
diff --git a/tests/text_processing/generate_text_for_display_test.php b/tests/text_processing/generate_text_for_display_test.php
index f2b0d6c78b..dba3713447 100644
--- a/tests/text_processing/generate_text_for_display_test.php
+++ b/tests/text_processing/generate_text_for_display_test.php
@@ -173,7 +173,7 @@ class phpbb_text_processing_generate_text_for_display_test extends phpbb_test_ca
 			),
 			array(
 				'<r><IMG src="http://localhost/mrgreen.gif"><s>[img]</s><URL url="http://localhost/mrgreen.gif">http://localhost/mrgreen.gif</URL><e>[/img]</e></IMG></r>',
-				'<img src="http://localhost/mrgreen.gif" alt="Image">'
+				'<img src="http://localhost/mrgreen.gif" class="postimage" alt="Image">'
 			),
 			array(
 				'<r><IMG src="http://localhost/mrgreen.gif"><s>[img]</s><URL url="http://localhost/mrgreen.gif">http://localhost/mrgreen.gif</URL><e>[/img]</e></IMG></r>',
diff --git a/tests/text_processing/tickets_data/PHPBB3-12195.html b/tests/text_processing/tickets_data/PHPBB3-12195.html
index d8e0f8d523..c286c0fee9 100644
--- a/tests/text_processing/tickets_data/PHPBB3-12195.html
+++ b/tests/text_processing/tickets_data/PHPBB3-12195.html
@@ -1 +1 @@
-<a href="//example.org/" class="postlink"><img src="//example.org/img.png" alt="Image"></a>
\ No newline at end of file
+<a href="//example.org/" class="postlink"><img src="//example.org/img.png" class="postimage" alt="Image"></a>
\ No newline at end of file