diff --git a/src/lib/FieldType/Mapper/ImageFormMapper.php b/src/lib/FieldType/Mapper/ImageFormMapper.php
index 84cc0a5865..25f7da3a33 100644
--- a/src/lib/FieldType/Mapper/ImageFormMapper.php
+++ b/src/lib/FieldType/Mapper/ImageFormMapper.php
@@ -97,7 +97,15 @@ private function getMimeTypesChoiceList(): array
     {
         $mimeTypeChoiceList = [];
         foreach ($this->allowedMimeTypes as $mimeType) {
-            $extensions = implode(', ', $this->mimeTypes->getExtensions($mimeType));
+            $extensions = implode(
+                ', ',
+                array_map(
+                    static function (string $extension): string {
+                        return '*.' . $extension;
+                    },
+                    $this->mimeTypes->getExtensions($mimeType)
+                )
+            );
             $label = explode('image/', $mimeType);
             $mimeTypeChoiceList[$label[1] . " ($extensions)"] = $mimeType;
         }