diff --git a/ants.go b/ants.go
index 3433028..4538625 100644
--- a/ants.go
+++ b/ants.go
@@ -48,12 +48,8 @@ const (
 )
 
 var (
-	// Error types for the Ants API.
-	//---------------------------------------------------------------------------
-
-	// ErrInvalidPoolSize will be returned when setting a negative number as pool capacity, this error will be only used
-	// by pool with func because pool without func can be infinite by setting up a negative capacity.
-	ErrInvalidPoolSize = errors.New("invalid size for pool")
+	//
+	//--------------------------Error types for the Ants API------------------------------
 
 	// ErrLackPoolFunc will be returned when invokers don't provide function for pool.
 	ErrLackPoolFunc = errors.New("must provide function for pool")
diff --git a/pool.go b/pool.go
index e5762f4..633de17 100644
--- a/pool.go
+++ b/pool.go
@@ -159,12 +159,12 @@ func (p *Pool) Submit(task func()) error {
 	return nil
 }
 
-// Running returns the number of the currently running goroutines.
+// Running returns the amount of the currently running goroutines.
 func (p *Pool) Running() int {
 	return int(atomic.LoadInt32(&p.running))
 }
 
-// Free returns the available goroutines to work, -1 indicates this pool is unlimited.
+// Free returns the amount of available goroutines to work, -1 indicates this pool is unlimited.
 func (p *Pool) Free() int {
 	c := p.Cap()
 	if c < 0 {
diff --git a/pool_func.go b/pool_func.go
index b2dfb68..ef2034b 100644
--- a/pool_func.go
+++ b/pool_func.go
@@ -176,12 +176,12 @@ func (p *PoolWithFunc) Invoke(args interface{}) error {
 	return nil
 }
 
-// Running returns the number of the currently running goroutines.
+// Running returns the amount of the currently running goroutines.
 func (p *PoolWithFunc) Running() int {
 	return int(atomic.LoadInt32(&p.running))
 }
 
-// Free returns an available goroutines to work, -1 indicates this pool is unlimited.
+// Free returns the amount of available goroutines to work, -1 indicates this pool is unlimited.
 func (p *PoolWithFunc) Free() int {
 	c := p.Cap()
 	if c < 0 {
@@ -242,7 +242,7 @@ func (p *PoolWithFunc) decRunning() {
 	atomic.AddInt32(&p.running, -1)
 }
 
-// retrieveWorker returns a available worker to run the tasks.
+// retrieveWorker returns an available worker to run the tasks.
 func (p *PoolWithFunc) retrieveWorker() (w *goWorkerWithFunc) {
 	spawnWorker := func() {
 		w = p.workerCache.Get().(*goWorkerWithFunc)