diff --git a/roaring/roaring_internal_test.go b/roaring/roaring_internal_test.go
index 7e1506ad2..12417c80f 100644
--- a/roaring/roaring_internal_test.go
+++ b/roaring/roaring_internal_test.go
@@ -657,27 +657,27 @@ func TestUnionArrayRun(t *testing.T) {
 	tests := []struct {
 		array []uint32
 		runs  []interval32
-		exp   []interval32
+		exp   []uint32
 	}{
 		{
 			array: []uint32{1, 4, 5, 7, 10, 11, 12},
 			runs:  []interval32{{start: 5, last: 10}},
-			exp:   []interval32{{start: 1, last: 1}, {start: 4, last: 12}},
+			exp:   []uint32{1, 4, 5, 6, 7, 8, 9, 10, 11, 12},
 		},
 		{
 			array: []uint32{},
 			runs:  []interval32{{start: 5, last: 10}},
-			exp:   []interval32{{start: 5, last: 10}},
+			exp:   []uint32{5, 6, 7, 8, 9, 10},
 		},
 		{
 			array: []uint32{1, 4, 5, 7, 10, 11, 12},
 			runs:  []interval32{},
-			exp:   []interval32{{start: 1, last: 1}, {start: 4, last: 5}, {start: 7, last: 7}, {start: 10, last: 12}},
+			exp:   []uint32{1, 4, 5, 7, 10, 11, 12},
 		},
 		{
 			array: []uint32{0, 1, 4, 5, 7, 10, 11, 12},
 			runs:  []interval32{{start: 0, last: 5}, {start: 7, last: 7}},
-			exp:   []interval32{{start: 0, last: 5}, {start: 7, last: 7}, {start: 10, last: 12}},
+			exp:   []uint32{0, 1, 2, 3, 4, 5, 7, 10, 11, 12},
 		},
 	}
 
@@ -685,7 +685,7 @@ func TestUnionArrayRun(t *testing.T) {
 		a.array = test.array
 		b.runs = test.runs
 		ret := unionArrayRun(a, b)
-		if !reflect.DeepEqual(ret.runs, test.exp) {
+		if !reflect.DeepEqual(ret.array, test.exp) {
 			t.Fatalf("test #%v expected %v, but got %v", i, test.exp, ret.array)
 		}
 	}