diff --git a/prometheus/counter.go b/prometheus/counter.go
index 273db5f..07f99f4 100644
--- a/prometheus/counter.go
+++ b/prometheus/counter.go
@@ -152,14 +152,22 @@ func (m *CounterVec) GetMetricWith(labels Labels) (Counter, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Add(42)
 func (m *CounterVec) WithLabelValues(lvs ...string) Counter {
-	return m.metricVec.withLabelValues(lvs...).(Counter)
+	c, err := m.GetMetricWithLabelValues(lvs...)
+	if err != nil {
+		panic(err)
+	}
+	return c
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
 func (m *CounterVec) With(labels Labels) Counter {
-	return m.metricVec.with(labels).(Counter)
+	c, err := m.GetMetricWith(labels)
+	if err != nil {
+		panic(err)
+	}
+	return c
 }
 
 // CounterFunc is a Counter whose value is determined at collect time by calling a
diff --git a/prometheus/gauge.go b/prometheus/gauge.go
index 13064da..a0cacec 100644
--- a/prometheus/gauge.go
+++ b/prometheus/gauge.go
@@ -138,14 +138,22 @@ func (m *GaugeVec) GetMetricWith(labels Labels) (Gauge, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Add(42)
 func (m *GaugeVec) WithLabelValues(lvs ...string) Gauge {
-	return m.metricVec.withLabelValues(lvs...).(Gauge)
+	g, err := m.GetMetricWithLabelValues(lvs...)
+	if err != nil {
+		panic(err)
+	}
+	return g
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Add(42)
 func (m *GaugeVec) With(labels Labels) Gauge {
-	return m.metricVec.with(labels).(Gauge)
+	g, err := m.GetMetricWith(labels)
+	if err != nil {
+		panic(err)
+	}
+	return g
 }
 
 // GaugeFunc is a Gauge whose value is determined at collect time by calling a
diff --git a/prometheus/histogram.go b/prometheus/histogram.go
index 6cc6e68..1b2d9b4 100644
--- a/prometheus/histogram.go
+++ b/prometheus/histogram.go
@@ -363,14 +363,22 @@ func (m *HistogramVec) GetMetricWith(labels Labels) (Observer, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Observe(42.21)
 func (m *HistogramVec) WithLabelValues(lvs ...string) Observer {
-	return m.metricVec.withLabelValues(lvs...).(Observer)
+	h, err := m.GetMetricWithLabelValues(lvs...)
+	if err != nil {
+		panic(err)
+	}
+	return h
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21)
 func (m *HistogramVec) With(labels Labels) Observer {
-	return m.metricVec.with(labels).(Observer)
+	h, err := m.GetMetricWith(labels)
+	if err != nil {
+		panic(err)
+	}
+	return h
 }
 
 type constHistogram struct {
diff --git a/prometheus/summary.go b/prometheus/summary.go
index 21c031e..b075301 100644
--- a/prometheus/summary.go
+++ b/prometheus/summary.go
@@ -480,14 +480,22 @@ func (m *SummaryVec) GetMetricWith(labels Labels) (Observer, error) {
 // error, WithLabelValues allows shortcuts like
 //     myVec.WithLabelValues("404", "GET").Observe(42.21)
 func (m *SummaryVec) WithLabelValues(lvs ...string) Observer {
-	return m.metricVec.withLabelValues(lvs...).(Observer)
+	s, err := m.GetMetricWithLabelValues(lvs...)
+	if err != nil {
+		panic(err)
+	}
+	return s
 }
 
 // With works as GetMetricWith, but panics where GetMetricWithLabels would have
 // returned an error. By not returning an error, With allows shortcuts like
 //     myVec.With(Labels{"code": "404", "method": "GET"}).Observe(42.21)
 func (m *SummaryVec) With(labels Labels) Observer {
-	return m.metricVec.with(labels).(Observer)
+	s, err := m.GetMetricWith(labels)
+	if err != nil {
+		panic(err)
+	}
+	return s
 }
 
 type constSummary struct {
diff --git a/prometheus/vec.go b/prometheus/vec.go
index 65d13fe..6e3a376 100644
--- a/prometheus/vec.go
+++ b/prometheus/vec.go
@@ -89,22 +89,6 @@ func (m *metricVec) getMetricWith(labels Labels) (Metric, error) {
 	return m.getOrCreateMetricWithLabels(h, labels), nil
 }
 
-func (m *metricVec) withLabelValues(lvs ...string) Metric {
-	metric, err := m.getMetricWithLabelValues(lvs...)
-	if err != nil {
-		panic(err)
-	}
-	return metric
-}
-
-func (m *metricVec) with(labels Labels) Metric {
-	metric, err := m.getMetricWith(labels)
-	if err != nil {
-		panic(err)
-	}
-	return metric
-}
-
 // DeleteLabelValues removes the metric where the variable labels are the same
 // as those passed in as labels (same order as the VariableLabels in Desc). It
 // returns true if a metric was deleted.