diff --git a/phpBB/docs/CHANGELOG.html b/phpBB/docs/CHANGELOG.html
index fc3efd08d3..d97c36d540 100644
--- a/phpBB/docs/CHANGELOG.html
+++ b/phpBB/docs/CHANGELOG.html
@@ -111,6 +111,7 @@
 		<li>[Fix] Do not display reported topic icon for shadow topics. (Bug #13970)</li>
 		<li>[Fix] Display popular topic based on posts within topic instead of replies within topic. (Bug #16099)</li>
 		<li>[Fix] Expand shown ban reason in unban screen to fully show long entries. (Bug #16234)</li>
+		<li>[Fix] Preserve alpha transparency for created thumbnails. (Bug #16575)</li>
 
 		<li>[Change] No longer allow the direct use of MULTI_INSERT in sql_build_array. sql_multi_insert() must be used.</li>
 		<li>[Change] Display warning in ACP if config.php file is left writable.</li>
diff --git a/phpBB/includes/functions_posting.php b/phpBB/includes/functions_posting.php
index 046922b8e3..4ce5fbd133 100644
--- a/phpBB/includes/functions_posting.php
+++ b/phpBB/includes/functions_posting.php
@@ -688,6 +688,10 @@ function create_thumbnail($source, $destination, $mimetype)
 					return false;
 				}
 
+				// Preserve alpha transparency (png for example)
+				@imagealphablending($new_image, false);
+				@imagesavealpha($new_image, true);
+
 				imagecopyresampled($new_image, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);
 			}