diff --git a/roaring/containers.go b/roaring/containers.go
index 08c8d25eb..133a30cf3 100644
--- a/roaring/containers.go
+++ b/roaring/containers.go
@@ -124,6 +124,14 @@ func (sc *SliceContainers) Size() int {
 
 }
 
+func (sc *SliceContainers) Count() uint64 {
+	n := uint64(0)
+	for i := range sc.containers {
+		n += uint64(sc.containers[i].n)
+	}
+	return n
+}
+
 func (sc *SliceContainers) seek(key uint64) (int, bool) {
 	i := search64(sc.keys, key)
 	found := true
@@ -153,6 +161,7 @@ func (si *SliceIterator) Next() bool {
 	si.key = si.e.keys[si.i]
 	si.value = si.e.containers[si.i]
 	si.i++
+
 	return true
 }
 
diff --git a/roaring/roaring.go b/roaring/roaring.go
index fafce4d59..8d132e7e0 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -93,6 +93,7 @@ type Containers interface {
 	// return the first container at or after key. found will be true if a
 	// container is found at key.
 	Iterator(key uint64) (citer ContainerIterator, found bool)
+	Count() uint64
 }
 
 type ContainerIterator interface {
@@ -218,12 +219,7 @@ func (b *Bitmap) Max() uint64 {
 
 // Count returns the number of bits set in the bitmap.
 func (b *Bitmap) Count() (n uint64) {
-	citer, _ := b.Containers.Iterator(0)
-	for citer.Next() {
-		_, c := citer.Value()
-		n += uint64(c.n)
-	}
-	return n
+	return b.Containers.Count()
 }
 
 // CountRange returns the number of bits set between [start, end).