diff --git a/pool.go b/pool.go
index 40f2ba1..755e32d 100644
--- a/pool.go
+++ b/pool.go
@@ -77,8 +77,10 @@ func (p *Pool) monitorAndClear() {
 				w.stop()
 				idleWorkers[i] = nil
 			}
-			n += 1
-			p.workers = idleWorkers[n:]
+			if n > 0 {
+				n += 1
+				p.workers = idleWorkers[n:]
+			}
 			p.lock.Unlock()
 		}
 	}()
diff --git a/pool_func.go b/pool_func.go
index 3d92730..f583600 100644
--- a/pool_func.go
+++ b/pool_func.go
@@ -78,8 +78,10 @@ func (p *PoolWithFunc) MonitorAndClear() {
 				w.stop()
 				idleWorkers[i] = nil
 			}
-			n += 1
-			p.workers = idleWorkers[n:]
+			if n > 0 {
+				n += 1
+				p.workers = idleWorkers[n:]
+			}
 			p.lock.Unlock()
 		}
 	}()