diff --git a/modules/document/document.item.php b/modules/document/document.item.php
index 732d25e17..dcf90e8d7 100644
--- a/modules/document/document.item.php
+++ b/modules/document/document.item.php
@@ -1146,9 +1146,14 @@ class DocumentItem extends BaseObject
 
 		// Call trigger for custom thumbnails.
 		$trigger_obj = (object)[
-			'document_srl' => $this->document_srl, 'width' => $width, 'height' => $height,
-			'image_type' => 'jpg', 'type' => $thumbnail_type, 'quality' => $config->thumbnail_quality,
-			'filename' => $thumbnail_file, 'url' => $thumbnail_url,
+			'document_srl' => $this->document_srl,
+			'width' => $width,
+			'height' => $height,
+			'image_type' => 'jpg',
+			'type' => $thumbnail_type,
+			'quality' => $config->thumbnail_quality,
+			'filename' => $thumbnail_file,
+			'url' => $thumbnail_url,
 		];
 		$output = ModuleHandler::triggerCall('document.getThumbnail', 'before', $trigger_obj);
 		clearstatcache(true, $thumbnail_file);
@@ -1220,8 +1225,16 @@ class DocumentItem extends BaseObject
 		// If not exists, file an image file from the content
 		if(!$source_file && $config->thumbnail_target !== 'attachment')
 		{
-			$external_image_min_width = min(100, round($trigger_obj->width * 0.3));
-			$external_image_min_height = min(100, round($trigger_obj->height * 0.3));
+			$external_image_min_width = is_numeric($trigger_obj->width) ? min(100, round(intval($trigger_obj->width) * 0.3)) : 100;
+			if($trigger_obj->height === 'auto')
+			{
+				$external_image_min_height = min(100, $external_image_min_width * 0.5);
+			}
+			else
+			{
+				$external_image_min_height = is_numeric($trigger_obj->height) ? min(100, round(intval($trigger_obj->height) * 0.3)) : 100;
+			}
+
 			preg_match_all("!<img\s[^>]*?src=(\"|')([^\"' ]*?)(\"|')!is", $content, $matches, PREG_SET_ORDER);
 			foreach($matches as $match)
 			{