diff --git a/src/counter.rs b/src/counter.rs
index 239e2982..8f36f4f3 100644
--- a/src/counter.rs
+++ b/src/counter.rs
@@ -44,10 +44,10 @@ impl<P: Atomic> GenericCounter<P> {
 
     /// Create a [`GenericCounter`] with the `opts` options.
     pub fn with_opts(opts: Opts) -> Result<Self> {
-        Self::with_opts_and_label_values(&opts, &[])
+        Self::with_opts_and_label_values::<&str>(&opts, &[])
     }
 
-    fn with_opts_and_label_values(opts: &Opts, label_values: &[&str]) -> Result<Self> {
+    fn with_opts_and_label_values<L: AsRef<str>>(opts: &Opts, label_values: &[L]) -> Result<Self> {
         let v = Value::new(opts, ValueType::Counter, P::T::from_i64(0), label_values)?;
         Ok(Self { v: Arc::new(v) })
     }
@@ -126,7 +126,7 @@ impl<P: Atomic> MetricVecBuilder for CounterVecBuilder<P> {
     type M = GenericCounter<P>;
     type P = Opts;
 
-    fn build(&self, opts: &Opts, vals: &[&str]) -> Result<Self::M> {
+    fn build<L: AsRef<str>>(&self, opts: &Opts, vals: &[L]) -> Result<Self::M> {
         Self::M::with_opts_and_label_values(opts, vals)
     }
 }
@@ -148,8 +148,11 @@ impl<P: Atomic> GenericCounterVec<P> {
     /// Create a new [`GenericCounterVec`] based on the provided
     /// [`Opts`] and partitioned by the given label names. At least one label name must be
     /// provided.
-    pub fn new(opts: Opts, label_names: &[&str]) -> Result<Self> {
-        let variable_names = label_names.iter().map(|s| (*s).to_owned()).collect();
+    pub fn new<L: AsRef<str>>(opts: Opts, label_names: &[L]) -> Result<Self> {
+        let variable_names = label_names
+            .iter()
+            .map(|s| (*s).as_ref().to_owned())
+            .collect();
         let opts = opts.variable_labels(variable_names);
         let metric_vec =
             MetricVec::create(proto::MetricType::COUNTER, CounterVecBuilder::new(), opts)?;
@@ -283,7 +286,10 @@ impl<P: Atomic> GenericLocalCounterVec<P> {
 
     /// Get a [`GenericLocalCounter`] by label values.
     /// See more [MetricVec::with_label_values].
-    pub fn with_label_values<'a>(&'a mut self, vals: &[&str]) -> &'a mut GenericLocalCounter<P> {
+    pub fn with_label_values<'a, L: AsRef<str>>(
+        &'a mut self,
+        vals: &[L],
+    ) -> &'a mut GenericLocalCounter<P> {
         let hash = self.vec.v.hash_label_values(vals).unwrap();
         let vec = &self.vec;
         self.local
@@ -293,7 +299,7 @@ impl<P: Atomic> GenericLocalCounterVec<P> {
 
     /// Remove a [`GenericLocalCounter`] by label values.
     /// See more [MetricVec::remove_label_values].
-    pub fn remove_label_values(&mut self, vals: &[&str]) -> Result<()> {
+    pub fn remove_label_values<L: AsRef<str>>(&mut self, vals: &[L]) -> Result<()> {
         let hash = self.vec.v.hash_label_values(vals)?;
         self.local.remove(&hash);
         self.vec.v.delete_label_values(vals)
diff --git a/src/gauge.rs b/src/gauge.rs
index 83eba2b1..d642b0ce 100644
--- a/src/gauge.rs
+++ b/src/gauge.rs
@@ -43,10 +43,10 @@ impl<P: Atomic> GenericGauge<P> {
 
     /// Create a [`GenericGauge`] with the `opts` options.
     pub fn with_opts(opts: Opts) -> Result<Self> {
-        Self::with_opts_and_label_values(&opts, &[])
+        Self::with_opts_and_label_values::<&str>(&opts, &[])
     }
 
-    fn with_opts_and_label_values(opts: &Opts, label_values: &[&str]) -> Result<Self> {
+    fn with_opts_and_label_values<L: AsRef<str>>(opts: &Opts, label_values: &[L]) -> Result<Self> {
         let v = Value::new(opts, ValueType::Gauge, P::T::from_i64(0), label_values)?;
         Ok(Self { v: Arc::new(v) })
     }
@@ -129,7 +129,7 @@ impl<P: Atomic> MetricVecBuilder for GaugeVecBuilder<P> {
     type M = GenericGauge<P>;
     type P = Opts;
 
-    fn build(&self, opts: &Opts, vals: &[&str]) -> Result<Self::M> {
+    fn build<L: AsRef<str>>(&self, opts: &Opts, vals: &[L]) -> Result<Self::M> {
         Self::M::with_opts_and_label_values(opts, vals)
     }
 }
@@ -151,8 +151,11 @@ impl<P: Atomic> GenericGaugeVec<P> {
     /// Create a new [`GenericGaugeVec`] based on the provided
     /// [`Opts`] and partitioned by the given label names. At least one label name must
     /// be provided.
-    pub fn new(opts: Opts, label_names: &[&str]) -> Result<Self> {
-        let variable_names = label_names.iter().map(|s| (*s).to_owned()).collect();
+    pub fn new<L: AsRef<str>>(opts: Opts, label_names: &[L]) -> Result<Self> {
+        let variable_names = label_names
+            .iter()
+            .map(|s| (*s).as_ref().to_owned())
+            .collect();
         let opts = opts.variable_labels(variable_names);
         let metric_vec = MetricVec::create(proto::MetricType::GAUGE, GaugeVecBuilder::new(), opts)?;
 
diff --git a/src/histogram.rs b/src/histogram.rs
index 78480541..b9500eae 100644
--- a/src/histogram.rs
+++ b/src/histogram.rs
@@ -327,7 +327,7 @@ pub struct HistogramCore {
 }
 
 impl HistogramCore {
-    pub fn new(opts: &HistogramOpts, label_values: &[&str]) -> Result<HistogramCore> {
+    pub fn new<L: AsRef<str>>(opts: &HistogramOpts, label_values: &[L]) -> Result<HistogramCore> {
         let desc = opts.describe()?;
 
         for name in &desc.variable_labels {
@@ -674,12 +674,12 @@ pub struct Histogram {
 impl Histogram {
     /// `with_opts` creates a [`Histogram`] with the `opts` options.
     pub fn with_opts(opts: HistogramOpts) -> Result<Histogram> {
-        Histogram::with_opts_and_label_values(&opts, &[])
+        Histogram::with_opts_and_label_values::<&str>(&opts, &[])
     }
 
-    fn with_opts_and_label_values(
+    fn with_opts_and_label_values<L: AsRef<str>>(
         opts: &HistogramOpts,
-        label_values: &[&str],
+        label_values: &[L],
     ) -> Result<Histogram> {
         let core = HistogramCore::new(opts, label_values)?;
 
@@ -783,7 +783,7 @@ impl MetricVecBuilder for HistogramVecBuilder {
     type M = Histogram;
     type P = HistogramOpts;
 
-    fn build(&self, opts: &HistogramOpts, vals: &[&str]) -> Result<Histogram> {
+    fn build<L: AsRef<str>>(&self, opts: &HistogramOpts, vals: &[L]) -> Result<Histogram> {
         Histogram::with_opts_and_label_values(opts, vals)
     }
 }
@@ -798,8 +798,11 @@ impl HistogramVec {
     /// Create a new [`HistogramVec`] based on the provided
     /// [`HistogramOpts`] and partitioned by the given label names. At least
     /// one label name must be provided.
-    pub fn new(opts: HistogramOpts, label_names: &[&str]) -> Result<HistogramVec> {
-        let variable_names = label_names.iter().map(|s| (*s).to_owned()).collect();
+    pub fn new<L: AsRef<str>>(opts: HistogramOpts, label_names: &[L]) -> Result<HistogramVec> {
+        let variable_names = label_names
+            .iter()
+            .map(|s| (*s).as_ref().to_owned())
+            .collect();
         let opts = opts.variable_labels(variable_names);
         let metric_vec =
             MetricVec::create(proto::MetricType::HISTOGRAM, HistogramVecBuilder {}, opts)?;
@@ -1168,7 +1171,7 @@ impl LocalHistogramVec {
 
     /// Get a [`LocalHistogram`] by label values.
     /// See more [`MetricVec::with_label_values`].
-    pub fn with_label_values<'a>(&'a mut self, vals: &[&str]) -> &'a LocalHistogram {
+    pub fn with_label_values<'a, L: AsRef<str>>(&'a mut self, vals: &[L]) -> &'a LocalHistogram {
         let hash = self.vec.v.hash_label_values(vals).unwrap();
         let vec = &self.vec;
         self.local
@@ -1178,7 +1181,7 @@ impl LocalHistogramVec {
 
     /// Remove a [`LocalHistogram`] by label values.
     /// See more [`MetricVec::remove_label_values`].
-    pub fn remove_label_values(&mut self, vals: &[&str]) -> Result<()> {
+    pub fn remove_label_values<L: AsRef<str>>(&mut self, vals: &[L]) -> Result<()> {
         let hash = self.vec.v.hash_label_values(vals)?;
         self.local.remove(&hash);
         self.vec.v.delete_label_values(vals)
diff --git a/src/value.rs b/src/value.rs
index 87b2ede2..a14a1eb4 100644
--- a/src/value.rs
+++ b/src/value.rs
@@ -37,11 +37,11 @@ pub struct Value<P: Atomic> {
 }
 
 impl<P: Atomic> Value<P> {
-    pub fn new<D: Describer>(
+    pub fn new<D: Describer, L: AsRef<str>>(
         describer: &D,
         val_type: ValueType,
         val: P::T,
-        label_values: &[&str],
+        label_values: &[L],
     ) -> Result<Self> {
         let desc = describer.describe()?;
         let label_pairs = make_label_pairs(&desc, label_values)?;
@@ -115,7 +115,7 @@ impl<P: Atomic> Value<P> {
     }
 }
 
-pub fn make_label_pairs(desc: &Desc, label_values: &[&str]) -> Result<Vec<LabelPair>> {
+pub fn make_label_pairs<L: AsRef<str>>(desc: &Desc, label_values: &[L]) -> Result<Vec<LabelPair>> {
     if desc.variable_labels.len() != label_values.len() {
         return Err(Error::InconsistentCardinality {
             expect: desc.variable_labels.len(),
@@ -136,7 +136,7 @@ pub fn make_label_pairs(desc: &Desc, label_values: &[&str]) -> Result<Vec<LabelP
     for (i, n) in desc.variable_labels.iter().enumerate() {
         let mut label_pair = LabelPair::default();
         label_pair.set_name(n.clone());
-        label_pair.set_value(label_values[i].to_owned());
+        label_pair.set_value(label_values[i].as_ref().to_owned());
         label_pairs.push(label_pair);
     }
 
diff --git a/src/vec.rs b/src/vec.rs
index 90508e93..f26eddad 100644
--- a/src/vec.rs
+++ b/src/vec.rs
@@ -21,7 +21,7 @@ pub trait MetricVecBuilder: Send + Sync + Clone {
     type P: Describer + Sync + Send + Clone;
 
     /// `build` builds a [`Metric`] with option and corresponding label names.
-    fn build(&self, _: &Self::P, _: &[&str]) -> Result<Self::M>;
+    fn build<L: AsRef<str>>(&self, _: &Self::P, _: &[L]) -> Result<Self::M>;
 }
 
 #[derive(Debug)]
@@ -49,7 +49,7 @@ impl<T: MetricVecBuilder> MetricVecCore<T> {
         m
     }
 
-    pub fn get_metric_with_label_values(&self, vals: &[&str]) -> Result<T::M> {
+    pub fn get_metric_with_label_values<L: AsRef<str>>(&self, vals: &[L]) -> Result<T::M> {
         let h = self.hash_label_values(vals)?;
 
         if let Some(metric) = self.children.read().get(&h).cloned() {
@@ -70,12 +70,20 @@ impl<T: MetricVecBuilder> MetricVecCore<T> {
         self.get_or_create_metric(h, &vals)
     }
 
-    pub fn delete_label_values(&self, vals: &[&str]) -> Result<()> {
+    pub fn delete_label_values<L: AsRef<str>>(&self, vals: &[L]) -> Result<()> {
         let h = self.hash_label_values(vals)?;
 
         let mut children = self.children.write();
         if children.remove(&h).is_none() {
-            return Err(Error::Msg(format!("missing label values {:?}", vals)));
+            let format_labels = vals
+                .iter()
+                .map(|l| l.as_ref())
+                .collect::<Vec<&str>>()
+                .join(", ");
+            return Err(Error::Msg(format!(
+                "missing label values [{}]",
+                format_labels
+            )));
         }
 
         Ok(())
@@ -97,7 +105,7 @@ impl<T: MetricVecBuilder> MetricVecCore<T> {
         self.children.write().clear();
     }
 
-    pub(crate) fn hash_label_values(&self, vals: &[&str]) -> Result<u64> {
+    pub(crate) fn hash_label_values<L: AsRef<str>>(&self, vals: &[L]) -> Result<u64> {
         if vals.len() != self.desc.variable_labels.len() {
             return Err(Error::InconsistentCardinality {
                 expect: self.desc.variable_labels.len(),
@@ -107,7 +115,7 @@ impl<T: MetricVecBuilder> MetricVecCore<T> {
 
         let mut h = FnvHasher::default();
         for val in vals {
-            h.write(val.as_bytes());
+            h.write(val.as_ref().as_bytes());
         }
 
         Ok(h.finish())
@@ -153,7 +161,7 @@ impl<T: MetricVecBuilder> MetricVecCore<T> {
         Ok(values)
     }
 
-    fn get_or_create_metric(&self, hash: u64, label_values: &[&str]) -> Result<T::M> {
+    fn get_or_create_metric<L: AsRef<str>>(&self, hash: u64, label_values: &[L]) -> Result<T::M> {
         let mut children = self.children.write();
         // Check exist first.
         if let Some(metric) = children.get(&hash).cloned() {
@@ -221,7 +229,7 @@ impl<T: MetricVecBuilder> MetricVec<T> {
     /// an alternative to avoid that type of mistake. For higher label numbers, the
     /// latter has a much more readable (albeit more verbose) syntax, but it comes
     /// with a performance overhead (for creating and processing the Labels map).
-    pub fn get_metric_with_label_values(&self, vals: &[&str]) -> Result<T::M> {
+    pub fn get_metric_with_label_values<L: AsRef<str>>(&self, vals: &[L]) -> Result<T::M> {
         self.v.get_metric_with_label_values(vals)
     }
 
@@ -254,7 +262,7 @@ impl<T: MetricVecBuilder> MetricVec<T> {
     /// ).unwrap();
     /// vec.with_label_values(&["404", "POST"]).inc()
     /// ```
-    pub fn with_label_values(&self, vals: &[&str]) -> T::M {
+    pub fn with_label_values<L: AsRef<str>>(&self, vals: &[L]) -> T::M {
         self.get_metric_with_label_values(vals).unwrap()
     }
 
@@ -277,7 +285,7 @@ impl<T: MetricVecBuilder> MetricVec<T> {
     /// alternative to avoid that type of mistake. For higher label numbers, the
     /// latter has a much more readable (albeit more verbose) syntax, but it comes
     /// with a performance overhead (for creating and processing the Labels map).
-    pub fn remove_label_values(&self, vals: &[&str]) -> Result<()> {
+    pub fn remove_label_values<L: AsRef<str>>(&self, vals: &[L]) -> Result<()> {
         self.v.delete_label_values(vals)
     }