diff --git a/proxyreader.go b/proxyreader.go
index 5a46ea7..0e87c2e 100644
--- a/proxyreader.go
+++ b/proxyreader.go
@@ -18,11 +18,10 @@
 
 type proxyWriterTo struct {
 	proxyReader
-	wt io.WriterTo
 }
 
 func (x proxyWriterTo) WriteTo(w io.Writer) (int64, error) {
-	n, err := x.wt.WriteTo(w)
+	n, err := x.ReadCloser.(io.WriterTo).WriteTo(w)
 	x.bar.IncrInt64(n)
 	return n, err
 }
@@ -42,12 +41,11 @@
 
 type ewmaProxyWriterTo struct {
 	ewmaProxyReader
-	wt proxyWriterTo
 }
 
 func (x ewmaProxyWriterTo) WriteTo(w io.Writer) (int64, error) {
 	start := time.Now()
-	n, err := x.wt.WriteTo(w)
+	n, err := x.ReadCloser.(io.WriterTo).WriteTo(w)
 	if n > 0 {
 		x.bar.DecoratorEwmaUpdate(time.Since(start))
 	}
@@ -58,14 +56,13 @@
 	pr := proxyReader{toReadCloser(r), b}
 	if hasEwma {
 		epr := ewmaProxyReader{pr}
-		if wt, ok := r.(io.WriterTo); ok {
-			pwt := proxyWriterTo{pr, wt}
-			return ewmaProxyWriterTo{epr, pwt}
+		if _, ok := r.(io.WriterTo); ok {
+			return ewmaProxyWriterTo{epr}
 		}
 		return epr
 	}
-	if wt, ok := r.(io.WriterTo); ok {
-		return proxyWriterTo{pr, wt}
+	if _, ok := r.(io.WriterTo); ok {
+		return proxyWriterTo{pr}
 	}
 	return pr
 }
diff --git a/proxyreader_test.go b/proxyreader_test.go
index 0f7f058..eaa972d 100644
--- a/proxyreader_test.go
+++ b/proxyreader_test.go
@@ -29,30 +29,30 @@
 
 type testWriterTo struct {
 	*testReader
-	wt io.WriterTo
+	called bool
 }
 
-func (wt testWriterTo) WriteTo(w io.Writer) (n int64, err error) {
+func (wt *testWriterTo) WriteTo(w io.Writer) (n int64, err error) {
 	wt.called = true
-	return wt.wt.WriteTo(w)
+	return wt.Reader.(io.WriterTo).WriteTo(w)
 }
 
 func TestProxyReader(t *testing.T) {
 	p := mpb.New(mpb.WithOutput(io.Discard))
 
-	tReader := &testReader{strings.NewReader(content), false}
+	reader := &testReader{strings.NewReader(content), false}
 
 	bar := p.AddBar(int64(len(content)))
 
 	var buf bytes.Buffer
-	_, err := io.Copy(&buf, bar.ProxyReader(tReader))
+	_, err := io.Copy(&buf, bar.ProxyReader(reader))
 	if err != nil {
 		t.Errorf("Error copying from reader: %+v\n", err)
 	}
 
 	p.Wait()
 
-	if !tReader.called {
+	if !reader.called {
 		t.Error("Read not called")
 	}
 
@@ -65,19 +65,19 @@
 	p := mpb.New(mpb.WithOutput(io.Discard))
 
 	var reader io.Reader = strings.NewReader(content)
-	tWriterTo := testWriterTo{&testReader{reader, false}, reader.(io.WriterTo)}
+	writerTo := &testWriterTo{&testReader{reader, false}, false}
 
 	bar := p.AddBar(int64(len(content)))
 
 	var buf bytes.Buffer
-	_, err := io.Copy(&buf, bar.ProxyReader(tWriterTo))
+	_, err := io.Copy(&buf, bar.ProxyReader(writerTo))
 	if err != nil {
 		t.Errorf("Error copying from reader: %+v\n", err)
 	}
 
 	p.Wait()
 
-	if !tWriterTo.called {
+	if !writerTo.called {
 		t.Error("WriteTo not called")
 	}