diff --git a/roaring/roaring.go b/roaring/roaring.go
index 903a04946..4d862da64 100644
--- a/roaring/roaring.go
+++ b/roaring/roaring.go
@@ -3177,6 +3177,9 @@ func xorArrayRun(a, b *container) *container {
 				j++
 			} else {
 				vb.start++
+				if vb.start > vb.last {
+					j++
+				}
 			}
 			i++
 		}
diff --git a/roaring/roaring_internal_test.go b/roaring/roaring_internal_test.go
index 6ee171fb4..4c18bc5ef 100644
--- a/roaring/roaring_internal_test.go
+++ b/roaring/roaring_internal_test.go
@@ -1711,56 +1711,43 @@ func TestWriteReadRun(t *testing.T) {
 }
 
 func TestXorArrayRun(t *testing.T) {
-	a := &container{array: []uint16{1, 5, 10, 11, 12}, container_type: ContainerArray}
-	b := &container{runs: []interval16{{start: 2, last: 10}, {start: 12, last: 13}, {start: 15, last: 16}}, container_type: ContainerRun}
-	exp := []uint16{1, 2, 3, 4, 6, 7, 8, 9, 11, 13, 15, 16}
-
-	//ret := xorArrayRun(a, b)
-	ret := xor(a, b)
-	if !reflect.DeepEqual(ret.array, exp) {
-		t.Fatalf("test #1 expected %v, but got %v", exp, ret.array)
+	tests := []struct {
+		a   *container
+		b   *container
+		exp *container
+	}{
+		{
+			a:   &container{array: []uint16{1, 5, 10, 11, 12}, container_type: ContainerArray},
+			b:   &container{runs: []interval16{{start: 2, last: 10}, {start: 12, last: 13}, {start: 15, last: 16}}, container_type: ContainerRun},
+			exp: &container{array: []uint16{1, 2, 3, 4, 6, 7, 8, 9, 11, 13, 15, 16}, container_type: ContainerArray, n: 12},
+		}, {
+			a:   &container{array: []uint16{1, 5, 10, 11, 12, 13, 14}, container_type: ContainerArray},
+			b:   &container{runs: []interval16{{start: 2, last: 10}, {start: 12, last: 13}, {start: 15, last: 16}}, container_type: ContainerRun},
+			exp: &container{array: []uint16{1, 2, 3, 4, 6, 7, 8, 9, 11, 14, 15, 16}, container_type: ContainerArray, n: 12},
+		}, {
+			a:   &container{array: []uint16{65535}, container_type: ContainerArray},
+			b:   &container{runs: []interval16{{start: 65534, last: 65535}}, container_type: ContainerRun},
+			exp: &container{array: []uint16{65534}, container_type: ContainerArray, n: 1},
+		}, {
+			a:   &container{array: []uint16{65535}, container_type: ContainerArray},
+			b:   &container{runs: []interval16{{start: 65535, last: 65535}}, container_type: ContainerRun},
+			exp: &container{array: []uint16{}, container_type: ContainerArray, n: 0},
+		},
 	}
 
-	ret = xor(b, a)
-	if !reflect.DeepEqual(ret.array, exp) {
-		t.Fatalf("test #2 expected %v, but got %v", exp, ret.array)
-	}
-	c := &container{array: []uint16{1, 5, 10, 11, 12, 13, 14}, container_type: ContainerArray}
-	//	exp = []int16{1, 2, 3, 4, 6, 7, 8, 9, 11, 14, 15, 16}
-	expr := []interval16{{start: 1, last: 4}, {start: 6, last: 9}, {start: 11, last: 11}, {start: 14, last: 16}}
-	ret = xor(b, c)
-	if !reflect.DeepEqual(ret.runs, expr) {
-		t.Fatalf("test #3 expected %v, but got %v", exp, ret.runs)
-	}
-	ret = xor(c, b)
-	if !reflect.DeepEqual(ret.runs, expr) {
-		t.Fatalf("test #4 expected %v, but got %v", exp, ret.array)
+	for i, test := range tests {
+		test.a.n = test.a.count()
+		test.b.n = test.b.count()
+		ret := xor(test.a, test.b)
+		if !reflect.DeepEqual(ret, test.exp) {
+			t.Fatalf("test #%v expected %v, but got %v", i, test.exp, ret)
+		}
+		ret = xor(test.b, test.a)
+		if !reflect.DeepEqual(ret, test.exp) {
+			t.Fatalf("test #%v.1 expected %v, but got %v", i, test.exp, ret)
+		}
 	}
 
-	a = &container{array: []uint16{65535}, container_type: ContainerArray}
-	b = &container{runs: []interval16{{start: 65534, last: 65535}}, container_type: ContainerRun}
-	exp = []uint16{65534}
-	ret = xor(a, b)
-	if !reflect.DeepEqual(ret.array, exp) {
-		t.Fatalf("test #5 expected %v, but got %v", exp, ret.array)
-	}
-
-	ret = xor(b, a)
-	if !reflect.DeepEqual(ret.array, exp) {
-		t.Fatalf("test #6 expected %v, but got %v", exp, ret.array)
-	}
-
-	b = &container{runs: []interval16{{start: 65535, last: 65535}}, container_type: ContainerRun}
-	exp = []uint16{}
-	ret = xor(a, b)
-	if !reflect.DeepEqual(ret.array, exp) {
-		t.Fatalf("test #7 expected %v, but got %v", exp, ret.array)
-	}
-
-	ret = xor(b, a)
-	if !reflect.DeepEqual(ret.array, exp) {
-		t.Fatalf("test #8 expected %v, but got %v", exp, ret.array)
-	}
 }
 
 //special case that didn't fit the xorrunrun table testing below.