diff --git a/src/calibre/ebooks/metadata/sources/covers.py b/src/calibre/ebooks/metadata/sources/covers.py
index bae9203f70..698abfbfce 100644
--- a/src/calibre/ebooks/metadata/sources/covers.py
+++ b/src/calibre/ebooks/metadata/sources/covers.py
@@ -100,7 +100,8 @@ def run_download(log, results, abort,
     wait_time = msprefs['wait_after_first_cover_result']
     found_results = {}
 
-    while True:
+    start_time = time.time()  # Use a global timeout to workaround misbehaving plugins that hang
+    while time.time() - start_time < 301:
         time.sleep(0.1)
         try:
             x = rq.get_nowait()