diff --git a/src/calibre/db/cache.py b/src/calibre/db/cache.py
index 839854e672..eb928efe2b 100644
--- a/src/calibre/db/cache.py
+++ b/src/calibre/db/cache.py
@@ -520,7 +520,9 @@ class Cache:
                     h.update(chunk)
                     pt.write(chunk)
             with self.write_lock:
-                self.backend.queue_fts_job(book_id, fmt, pt.name, sz, h.hexdigest())
+                queued = self.backend.queue_fts_job(book_id, fmt, pt.name, sz, h.hexdigest())
+                if not queued:  # means a dirtied book was removed
+                    self._update_fts_indexing_numbers()
                 return self.backend.fts_has_idle_workers
 
         def loop_while_more_available():
diff --git a/src/calibre/db/fts/pool.py b/src/calibre/db/fts/pool.py
index e7dbeb8fab..995a55c265 100644
--- a/src/calibre/db/fts/pool.py
+++ b/src/calibre/db/fts/pool.py
@@ -171,7 +171,7 @@ class Pool:
 
     @property
     def num_of_idle_workers(self):
-        return sum(1 if w.working else 0 for w in self.workers)
+        return sum(0 if w.working else 1 for w in self.workers)
 
     def check_for_work(self):
         self.initialize()