diff --git a/mod/forum/lib.php b/mod/forum/lib.php
index 72af47cda4d2b..ff9485ef4b461 100644
--- a/mod/forum/lib.php
+++ b/mod/forum/lib.php
@@ -2581,7 +2581,14 @@ function forum_print_attachments($post, $cm, $type) {
         foreach ($files as $file) {
             $filename = $file->get_filename();
             $mimetype = $file->get_mimetype();
-            $iconimage = $OUTPUT->pix_icon(file_file_icon($file), get_mimetype_description($file), 'moodle', array('class' => 'icon'));
+            $iconimage = $OUTPUT->pix_icon(file_file_icon($file),
+                    get_mimetype_description($file),
+                    'moodle',
+                    [
+                            'class' => 'icon',
+                            'style' => 'max-width: 24px; max-height: 24px; vertical-align: middle;',
+                    ]
+            );
             $path = file_encode_url($CFG->wwwroot.'/pluginfile.php', '/'.$context->id.'/mod_forum/attachment/'.$post->id.'/'.$filename);
 
             if ($type == 'html') {