diff --git a/src/calibre/ebooks/metadata/sources/update.py b/src/calibre/ebooks/metadata/sources/update.py
index c6b7292fd9..a2403d65a1 100644
--- a/src/calibre/ebooks/metadata/sources/update.py
+++ b/src/calibre/ebooks/metadata/sources/update.py
@@ -59,8 +59,12 @@ def patch_search_engines(src):
     global current_search_engines
     src = src.encode('utf-8')
     ns = {}
-    exec(src, ns)
-    mcv = ns.get('minimum_calibre_version')
+    try:
+        exec(src, ns)
+    except Exception:
+        mcv = None
+    else:
+        mcv = ns.get('minimum_calibre_version')
     if mcv is None or mcv > numeric_version:
         return
     cv = ns.get('current_version')