diff --git a/head_bench_test.go b/head_bench_test.go
index 68505ea2c..0b0391e0a 100644
--- a/head_bench_test.go
+++ b/head_bench_test.go
@@ -56,20 +56,21 @@ func BenchmarkHeadPostingForMatchers(b *testing.B) {
 		testutil.Ok(b, h.Close())
 	}()
 
-	var hash uint64
+	var ref uint64
+
+	addSeries := func(l labels.Labels) {
+		ref++
+		h.getOrCreateWithID(ref, l.Hash(), l)
+	}
+
 	for n := 0; n < 10; n++ {
 		for i := 0; i < 100000; i++ {
-			h.getOrCreate(hash, labels.FromStrings("i", strconv.Itoa(i), "n", strconv.Itoa(i), "j", "foo"))
-			hash++
+			addSeries(labels.FromStrings("i", strconv.Itoa(i), "n", strconv.Itoa(n), "j", "foo"))
 			// Have some series that won't be matched, to properly test inverted matches.
-			h.getOrCreate(hash, labels.FromStrings("i", strconv.Itoa(i), "n", strconv.Itoa(i), "j", "bar"))
-			hash++
-			h.getOrCreate(hash, labels.FromStrings("i", strconv.Itoa(i), "n", "0_"+strconv.Itoa(i), "j", "bar"))
-			hash++
-			h.getOrCreate(hash, labels.FromStrings("i", strconv.Itoa(i), "n", "1_"+strconv.Itoa(i), "j", "bar"))
-			hash++
-			h.getOrCreate(hash, labels.FromStrings("i", strconv.Itoa(i), "n", "2_"+strconv.Itoa(i), "j", "bar"))
-			hash++
+			addSeries(labels.FromStrings("i", strconv.Itoa(i), "n", strconv.Itoa(n), "j", "bar"))
+			addSeries(labels.FromStrings("i", strconv.Itoa(i), "n", "0_"+strconv.Itoa(n), "j", "bar"))
+			addSeries(labels.FromStrings("i", strconv.Itoa(i), "n", "1_"+strconv.Itoa(n), "j", "bar"))
+			addSeries(labels.FromStrings("i", strconv.Itoa(i), "n", "2_"+strconv.Itoa(n), "j", "foo"))
 		}
 	}
 
@@ -100,6 +101,7 @@ func BenchmarkHeadPostingForMatchers(b *testing.B) {
 		{`i!=""`, []labels.Matcher{iNotEmpty}},
 		{`n="1",i=~".*",j="foo"`, []labels.Matcher{n1, iStar, jFoo}},
 		{`n="1",i=~".*",i!="2",j="foo"`, []labels.Matcher{n1, iStar, iNot2, jFoo}},
+		{`n="1",i!=""`, []labels.Matcher{n1, iNotEmpty}},
 		{`n="1",i!="",j="foo"`, []labels.Matcher{n1, iNotEmpty, jFoo}},
 		{`n="1",i=~".+",j="foo"`, []labels.Matcher{n1, iPlus, jFoo}},
 		{`n="1",i=~"1.+",j="foo"`, []labels.Matcher{n1, i1Plus, jFoo}},
diff --git a/index/postings.go b/index/postings.go
index cdad93953..bb7b5837a 100644
--- a/index/postings.go
+++ b/index/postings.go
@@ -404,7 +404,6 @@ func (h *postingsHeap) Pop() interface{} {
 type mergedPostings struct {
 	h          postingsHeap
 	initilized bool
-	heaped     bool
 	cur        uint64
 	err        error
 }
@@ -434,12 +433,9 @@ func (it *mergedPostings) Next() bool {
 		return false
 	}
 
-	if !it.heaped {
-		heap.Init(&it.h)
-		it.heaped = true
-	}
 	// The user must issue an initial Next.
 	if !it.initilized {
+		heap.Init(&it.h)
 		it.cur = it.h[0].At()
 		it.initilized = true
 		return true
@@ -477,33 +473,24 @@ func (it *mergedPostings) Seek(id uint64) bool {
 			return false
 		}
 	}
-	if it.cur >= id {
-		return true
-	}
-	// Heapifying when there is lots of Seeks is inefficient,
-	// mark to be re-heapified on the Next() call.
-	it.heaped = false
-	lowest := ^uint64(0)
-	n := 0
-	for _, i := range it.h {
-		if i.Seek(id) {
-			it.h[n] = i
-			n++
-			if i.At() < lowest {
-				lowest = i.At()
-			}
-		} else {
-			if i.Err() != nil {
-				it.err = i.Err()
+	for it.cur < id {
+		cur := it.h[0]
+		if !cur.Seek(id) {
+			heap.Pop(&it.h)
+			if cur.Err() != nil {
+				it.err = cur.Err()
 				return false
 			}
+			if it.h.Len() == 0 {
+				return false
+			}
+		} else {
+			// Value of top of heap has changed, re-heapify.
+			heap.Fix(&it.h, 0)
 		}
+
+		it.cur = it.h[0].At()
 	}
-	it.h = it.h[:n]
-	if len(it.h) == 0 {
-		return false
-	}
-	it.cur = lowest
 	return true
 }
 
diff --git a/querier.go b/querier.go
index b7116c27e..9d99de083 100644
--- a/querier.go
+++ b/querier.go
@@ -332,15 +332,6 @@ func PostingsForMatchers(ix IndexReader, ms ...labels.Matcher) (index.Postings,
 	it := index.Intersect(its...)
 
 	for _, n := range notIts {
-		if _, ok := n.(*index.ListPostings); !ok {
-			// Best to pre-calculate the merged lists via next rather than have a ton
-			// of seeks in Without.
-			pl, err := index.ExpandPostings(n)
-			if err != nil {
-				return nil, err
-			}
-			n = index.NewListPostings(pl)
-		}
 		it = index.Without(it, n)
 	}