diff --git a/src/encoding.rs b/src/encoding.rs
index c206a1c..c9c9a83 100644
--- a/src/encoding.rs
+++ b/src/encoding.rs
@@ -468,12 +468,19 @@ impl EncodeLabelValue for &str {
         Ok(())
     }
 }
+
 impl EncodeLabelValue for String {
     fn encode(&self, encoder: &mut LabelValueEncoder) -> Result<(), std::fmt::Error> {
         EncodeLabelValue::encode(&self.as_str(), encoder)
     }
 }
 
+impl EncodeLabelValue for &String {
+    fn encode(&self, encoder: &mut LabelValueEncoder) -> Result<(), std::fmt::Error> {
+        EncodeLabelValue::encode(&self.as_str(), encoder)
+    }
+}
+
 impl<'a> EncodeLabelValue for Cow<'a, str> {
     fn encode(&self, encoder: &mut LabelValueEncoder) -> Result<(), std::fmt::Error> {
         EncodeLabelValue::encode(&self.as_ref(), encoder)