diff --git a/src/calibre/library/database2.py b/src/calibre/library/database2.py
index dc82825607..495cd9b685 100644
--- a/src/calibre/library/database2.py
+++ b/src/calibre/library/database2.py
@@ -1373,7 +1373,9 @@ class LibraryDatabase2(LibraryDatabase, SchemaUpgrade, CustomColumns):
             if r is not None:
                 if (now - r[self.FIELD_MAP['timestamp']]) > delta:
                     tags = r[self.FIELD_MAP['tags']]
-                    if tags and tag in tags.lower():
+                    tags = tags.lower().split() if tags else []
+                    tags = [tag.strip() for tag in tags if tag.strip()]
+                    if tag in tags:
                         yield r[self.FIELD_MAP['id']]
 
     def get_next_series_num_for(self, series):