diff --git a/prometheus/promhttp/http.go b/prometheus/promhttp/http.go
index a9c4819c4..09b8d2fbe 100644
--- a/prometheus/promhttp/http.go
+++ b/prometheus/promhttp/http.go
@@ -160,15 +160,11 @@ func HandlerForTransactional(reg prometheus.TransactionalGatherer, opts HandlerO
 		}
 
 		var contentType expfmt.Format
-		if req.Header != nil {
-			fmt.Println("NEGOTIATE content type received: ", req.Header)
-		}
 		if opts.EnableOpenMetrics {
 			contentType = expfmt.NegotiateIncludingOpenMetrics(req.Header)
 		} else {
 			contentType = expfmt.Negotiate(req.Header)
 		}
-		fmt.Println("NEGOTIATE deduced content type: ", contentType)
 		header := rsp.Header()
 		header.Set(contentTypeHeader, string(contentType))
 
@@ -211,7 +207,6 @@ func HandlerForTransactional(reg prometheus.TransactionalGatherer, opts HandlerO
 		}
 
 		for _, mf := range mfs {
-			// This is the place where the metric family is getting escaped on the receive side.
 			if handleError(enc.Encode(mf)) {
 				return
 			}
diff --git a/prometheus/push/push.go b/prometheus/push/push.go
index b2c32f429..e524aa130 100644
--- a/prometheus/push/push.go
+++ b/prometheus/push/push.go
@@ -109,7 +109,7 @@ func New(url, job string) *Pusher {
 		gatherers:  prometheus.Gatherers{reg},
 		registerer: reg,
 		client:     &http.Client{},
-		expfmt:     expfmt.FmtProtoDelim,
+		expfmt:     expfmt.NewFormat(expfmt.TypeProtoDelim),
 	}
 }
 
diff --git a/prometheus/push/push_test.go b/prometheus/push/push_test.go
index f90740853..d30d17550 100644
--- a/prometheus/push/push_test.go
+++ b/prometheus/push/push_test.go
@@ -84,7 +84,7 @@ func TestPush(t *testing.T) {
 	}
 
 	buf := &bytes.Buffer{}
-	enc := expfmt.NewEncoder(buf, expfmt.FmtProtoDelim)
+	enc := expfmt.NewEncoder(buf, expfmt.NewFormat(expfmt.TypeProtoDelim))
 
 	for _, mf := range mfs {
 		if err := enc.Encode(mf); err != nil {
diff --git a/prometheus/registry_test.go b/prometheus/registry_test.go
index dca36fe58..61fc1c5cb 100644
--- a/prometheus/registry_test.go
+++ b/prometheus/registry_test.go
@@ -92,7 +92,7 @@ func testHandler(t testing.TB) {
 		},
 	}
 	externalBuf := &bytes.Buffer{}
-	enc := expfmt.NewEncoder(externalBuf, expfmt.FmtProtoDelim)
+	enc := expfmt.NewEncoder(externalBuf, expfmt.NewFormat(expfmt.TypeProtoDelim))
 	if err := enc.Encode(externalMetricFamily); err != nil {
 		t.Fatal(err)
 	}
@@ -162,7 +162,7 @@ metric: <
 		},
 	}
 	buf := &bytes.Buffer{}
-	enc = expfmt.NewEncoder(buf, expfmt.FmtProtoDelim)
+	enc = expfmt.NewEncoder(buf, expfmt.NewFormat(expfmt.TypeProtoDelim))
 	if err := enc.Encode(expectedMetricFamily); err != nil {
 		t.Fatal(err)
 	}
@@ -361,7 +361,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: []byte{},
 			},
@@ -372,7 +372,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: []byte{},
 			},
@@ -383,7 +383,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: []byte{},
 			},
@@ -394,7 +394,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited; escaping=values`,
 				},
 				body: []byte{},
 			},
@@ -405,7 +405,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: expectedMetricFamilyAsText,
 			},
@@ -417,7 +417,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited; escaping=values`,
 				},
 				body: expectedMetricFamilyAsBytes,
 			},
@@ -429,7 +429,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: externalMetricFamilyAsText,
 			},
@@ -441,7 +441,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited; escaping=values`,
 				},
 				body: externalMetricFamilyAsBytes,
 			},
@@ -453,7 +453,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited; escaping=values`,
 				},
 				body: bytes.Join(
 					[][]byte{
@@ -472,7 +472,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: []byte{},
 			},
@@ -483,7 +483,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: expectedMetricFamilyAsText,
 			},
@@ -495,7 +495,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: bytes.Join(
 					[][]byte{
@@ -514,7 +514,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=delimited; escaping=values`,
 				},
 				body: bytes.Join(
 					[][]byte{
@@ -533,7 +533,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=text`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=text; escaping=values`,
 				},
 				body: bytes.Join(
 					[][]byte{
@@ -552,7 +552,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=compact-text`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=compact-text; escaping=values`,
 				},
 				body: bytes.Join(
 					[][]byte{
@@ -571,7 +571,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=compact-text`,
+					"Content-Type": `application/vnd.google.protobuf; proto=io.prometheus.client.MetricFamily; encoding=compact-text; escaping=values`,
 				},
 				body: bytes.Join(
 					[][]byte{
@@ -609,7 +609,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: expectedMetricFamilyAsText,
 			},
@@ -666,7 +666,7 @@ collected metric "broken_metric" { label:<name:"foo" value:"bar" > label:<name:"
 			},
 			out: output{
 				headers: map[string]string{
-					"Content-Type": `text/plain; version=0.0.4; charset=utf-8`,
+					"Content-Type": `text/plain; version=0.0.4; charset=utf-8; escaping=values`,
 				},
 				body: bytes.Join(
 					[][]byte{
diff --git a/prometheus/testutil/promlint/promlint.go b/prometheus/testutil/promlint/promlint.go
index 6edda56f3..ea46f38ec 100644
--- a/prometheus/testutil/promlint/promlint.go
+++ b/prometheus/testutil/promlint/promlint.go
@@ -68,7 +68,7 @@ func (l *Linter) Lint() ([]Problem, error) {
 	var problems []Problem
 
 	if l.r != nil {
-		d := expfmt.NewDecoder(l.r, expfmt.FmtText_1_0_0)
+		d := expfmt.NewDecoder(l.r, expfmt.NewFormat(expfmt.TypeTextPlain))
 
 		mf := &dto.MetricFamily{}
 		for {
diff --git a/prometheus/testutil/testutil.go b/prometheus/testutil/testutil.go
index cb3958286..9dce15eaf 100644
--- a/prometheus/testutil/testutil.go
+++ b/prometheus/testutil/testutil.go
@@ -265,13 +265,13 @@ func compareMetricFamilies(got, expected []*dto.MetricFamily, metricNames ...str
 // result.
 func compare(got, want []*dto.MetricFamily) error {
 	var gotBuf, wantBuf bytes.Buffer
-	enc := expfmt.NewEncoder(&gotBuf, expfmt.FmtText_1_0_0)
+	enc := expfmt.NewEncoder(&gotBuf, expfmt.NewFormat(expfmt.TypeTextPlain))
 	for _, mf := range got {
 		if err := enc.Encode(mf); err != nil {
 			return fmt.Errorf("encoding gathered metrics failed: %w", err)
 		}
 	}
-	enc = expfmt.NewEncoder(&wantBuf, expfmt.FmtText_1_0_0)
+	enc = expfmt.NewEncoder(&wantBuf, expfmt.NewFormat(expfmt.TypeTextPlain))
 	for _, mf := range want {
 		if err := enc.Encode(mf); err != nil {
 			return fmt.Errorf("encoding expected metrics failed: %w", err)