diff --git a/typo3/sysext/backend/Classes/Form/Container/InlineRecordContainer.php b/typo3/sysext/backend/Classes/Form/Container/InlineRecordContainer.php
index 415ca2c1ad767b98981ca7750028669410a17c73..095f1ec9a7fc7ef96a5631f84012eb667c28b8de 100644
--- a/typo3/sysext/backend/Classes/Form/Container/InlineRecordContainer.php
+++ b/typo3/sysext/backend/Classes/Form/Container/InlineRecordContainer.php
@@ -340,15 +340,21 @@ class InlineRecordContainer extends AbstractContainer
                         $imageSetup['crop'] = $rec['crop'];
                     }
                     $imageSetup = array_merge(['width' => '45', 'height' => '45c'], $imageSetup);
-                    $processedImage = $fileObject->process(ProcessedFile::CONTEXT_IMAGEPREVIEW, $imageSetup);
-                    // Only use a thumbnail if the processing process was successful by checking if image width is set
-                    if ($processedImage->getProperty('width')) {
-                        $imageUrl = $processedImage->getPublicUrl(true);
-                        $thumbnail = '<img src="' . $imageUrl . '" ' .
-                            'width="' . $processedImage->getProperty('width') . '" ' .
-                            'height="' . $processedImage->getProperty('height') . '" ' .
-                            'alt="' . htmlspecialchars($altText) . '" ' .
-                            'title="' . htmlspecialchars($altText) . '">';
+
+                    if ($GLOBALS['TYPO3_CONF_VARS']['GFX']['thumbnails']
+                        && GeneralUtility::inList($GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext'], $fileObject->getProperty('extension'))) {
+                        $processedImage = $fileObject->process(ProcessedFile::CONTEXT_IMAGEPREVIEW, $imageSetup);
+                        // Only use a thumbnail if the processing process was successful by checking if image width is set
+                        if ($processedImage->getProperty('width')) {
+                            $imageUrl = $processedImage->getPublicUrl(true);
+                            $thumbnail = '<img src="' . $imageUrl . '" ' .
+                                'width="' . $processedImage->getProperty('width') . '" ' .
+                                'height="' . $processedImage->getProperty('height') . '" ' .
+                                'alt="' . htmlspecialchars($altText) . '" ' .
+                                'title="' . htmlspecialchars($altText) . '">';
+                        }
+                    } else {
+                        $thumbnail = '';
                     }
                 }
             }
diff --git a/typo3/sysext/backend/Classes/Utility/BackendUtility.php b/typo3/sysext/backend/Classes/Utility/BackendUtility.php
index e153658dbd197ca074977773591bf9c527ef3a26..99e90d87f894dca2c181fdd03493d4fe65f0059a 100644
--- a/typo3/sysext/backend/Classes/Utility/BackendUtility.php
+++ b/typo3/sysext/backend/Classes/Utility/BackendUtility.php
@@ -1286,7 +1286,7 @@ class BackendUtility
                 // Preview web image or media elements
                 if ($GLOBALS['TYPO3_CONF_VARS']['GFX']['thumbnails']
                     && GeneralUtility::inList(
-                        $GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext'] . ',' . $GLOBALS['TYPO3_CONF_VARS']['SYS']['mediafile_ext'],
+                        $GLOBALS['TYPO3_CONF_VARS']['GFX']['imagefile_ext'],
                         $fileReferenceObject->getExtension()
                     )
                 ) {