diff --git a/roaring/roaring.go b/roaring/roaring.go
index 0a91c4493..1631c7772 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -1214,7 +1214,7 @@ func intersectionCountArrayArray(a, b *container) (n uint64) {
 	return n
 }
 
-func intersectionCountArrayBitmap(a, b *container) (n uint64) {
+func intersectionCountArrayBitmapOld(a, b *container) (n uint64) {
 	// Copy array header so we can shrink it.
 	array := a.array
 	if len(array) == 0 {
@@ -1256,6 +1256,18 @@ func intersectionCountArrayBitmap(a, b *container) (n uint64) {
 	return n
 }
 
+func intersectionCountArrayBitmap(a, b *container) (n uint64) {
+	for _, val := range a.array {
+		i := val / 64
+		if i >= uint32(len(b.bitmap)) {
+			break
+		}
+		off := val % 64
+		n += (b.bitmap[i] & (1 << off)) >> off
+	}
+	return n
+}
+
 func intersectionCountBitmapBitmap(a, b *container) (n uint64) {
 	return popcntAndSlice(a.bitmap, b.bitmap)
 }
diff --git a/roaring/roaring_internal_test.go b/roaring/roaring_internal_test.go
index 5cff4a30f..8fd64cbcb 100644
--- a/roaring/roaring_internal_test.go
+++ b/roaring/roaring_internal_test.go
@@ -1,8 +1,6 @@
 package roaring
 
-import (
-	"testing"
-)
+import "testing"
 
 func TestBitmapCountRange(t *testing.T) {
 	c := container{}
@@ -27,3 +25,48 @@ func TestBitmapCountRange(t *testing.T) {
 		}
 	}
 }
+
+func TestIntersectionCountArrayBitmap2(t *testing.T) {
+	a, b := &container{}, &container{}
+	tests := []struct {
+		array  []uint32
+		bitmap []uint64
+		exp    uint64
+	}{
+		{
+			array:  []uint32{0},
+			bitmap: []uint64{1},
+			exp:    1,
+		},
+		{
+			array:  []uint32{0, 1},
+			bitmap: []uint64{3},
+			exp:    2,
+		},
+		{
+			array:  []uint32{64, 128, 129, 2000},
+			bitmap: []uint64{932421, 2},
+			exp:    0,
+		},
+		{
+			array:  []uint32{0, 65, 130, 195},
+			bitmap: []uint64{255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255},
+			exp:    4,
+		},
+		{
+			array:  []uint32{63, 120, 543, 639, 12000},
+			bitmap: []uint64{0x8000000000000000, 0, 0, 0, 0, 0, 0, 0, 0, 0x8000000000000000},
+			exp:    2,
+		},
+	}
+
+	for i, test := range tests {
+		a.array = test.array
+		b.bitmap = test.bitmap
+		ret1 := intersectionCountArrayBitmapOld(a, b)
+		ret2 := intersectionCountArrayBitmap(a, b)
+		if ret1 != ret2 || ret2 != test.exp {
+			t.Fatalf("test #%v intersectCountArrayBitmap fail orig: %v new: %v exp: %v", i, ret1, ret2, test.exp)
+		}
+	}
+}