diff --git a/retrieval/target.go b/retrieval/target.go
index ca5cc0db7..07628c70e 100644
--- a/retrieval/target.go
+++ b/retrieval/target.go
@@ -305,6 +305,7 @@ func (app *countingAppender) Append(s *model.Sample) error {
 // It returns a label set before relabeling was applied as the second return value.
 // Returns a nil label set if the target is dropped during relabeling.
 func populateLabels(lset model.LabelSet, cfg *config.ScrapeConfig) (res, orig model.LabelSet, err error) {
+	lset = lset.Clone()
 	if _, ok := lset[model.AddressLabel]; !ok {
 		return nil, nil, fmt.Errorf("no address")
 	}
diff --git a/retrieval/targetmanager_test.go b/retrieval/targetmanager_test.go
index dc4568a95..a8b629204 100644
--- a/retrieval/targetmanager_test.go
+++ b/retrieval/targetmanager_test.go
@@ -140,10 +140,14 @@ func TestPopulateLabels(t *testing.T) {
 		},
 	}
 	for i, c := range cases {
+		in := c.in.Clone()
 		res, orig, err := populateLabels(c.in, c.cfg)
 		if err != nil {
 			t.Fatalf("case %d: %s", i, err)
 		}
+		if !reflect.DeepEqual(c.in, in) {
+			t.Errorf("case %d: input lset was changed was\n\t%+v\n now\n\t%+v", i, in, c.in)
+		}
 		if !reflect.DeepEqual(res, c.res) {
 			t.Errorf("case %d: expected res\n\t%+v\n got\n\t%+v", i, c.res, res)
 		}
diff --git a/storage/local/persistence.go b/storage/local/persistence.go
index 4d2733496..5015fb3c6 100644
--- a/storage/local/persistence.go
+++ b/storage/local/persistence.go
@@ -310,6 +310,7 @@ func newPersistence(
 		dirtyFileName:  dirtyPath,
 		fLock:          fLock,
 		shouldSync:     shouldSync,
+		minShrinkRatio: minShrinkRatio,
 		// Create buffers of length 3*chunkLenWithHeader by default because that is still reasonably small
 		// and at the same time enough for many uses. The contract is to never return buffer smaller than
 		// that to the pool so that callers can rely on a minimum buffer size.
diff --git a/storage/local/persistence_test.go b/storage/local/persistence_test.go
index 27f620366..e88b17592 100644
--- a/storage/local/persistence_test.go
+++ b/storage/local/persistence_test.go
@@ -42,7 +42,7 @@ var (
 func newTestPersistence(t *testing.T, encoding chunk.Encoding) (*persistence, testutil.Closer) {
 	chunk.DefaultEncoding = encoding
 	dir := testutil.NewTemporaryDirectory("test_persistence", t)
-	p, err := newPersistence(dir.Path(), false, false, func() bool { return false }, 0.1)
+	p, err := newPersistence(dir.Path(), false, false, func() bool { return false }, 0.15)
 	if err != nil {
 		dir.Close()
 		t.Fatal(err)
@@ -173,6 +173,25 @@ func testPersistLoadDropChunks(t *testing.T, encoding chunk.Encoding) {
 
 		}
 	}
+	// Try to drop one chunk, which must be prevented by the shrink ratio.
+	for fp, _ := range fpToChunks {
+		firstTime, offset, numDropped, allDropped, err := p.dropAndPersistChunks(fp, 1, nil)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if offset != 0 {
+			t.Errorf("want offset 0, got %d", offset)
+		}
+		if firstTime != 0 {
+			t.Errorf("want first time 0, got %d", firstTime)
+		}
+		if numDropped != 0 {
+			t.Errorf("want 0 dropped chunks, got %v", numDropped)
+		}
+		if allDropped {
+			t.Error("all chunks dropped")
+		}
+	}
 	// Drop half of the chunks.
 	for fp, expectedChunks := range fpToChunks {
 		firstTime, offset, numDropped, allDropped, err := p.dropAndPersistChunks(fp, 5, nil)