diff --git a/yt_dlp/extractor/nhk.py b/yt_dlp/extractor/nhk.py
index 216cc8b414..d15a068ad1 100644
--- a/yt_dlp/extractor/nhk.py
+++ b/yt_dlp/extractor/nhk.py
@@ -769,7 +769,7 @@ def _get_thumbnails(self, thumbs, name, preference=-1):
         if thumbs is None or len(thumbs) == 0:
             return []
         for size, thumb in thumbs:
-            if size == 'copyright':
+            if size == 'copyright' or not isinstance(thumb, dict):
                 continue
             thumbnails.append({**thumb,
                                'preference': preference,