diff --git a/micrometer-commons/src/main/java/io/micrometer/common/KeyValue.java b/micrometer-commons/src/main/java/io/micrometer/common/KeyValue.java
index f18fac173e..58b5551124 100644
--- a/micrometer-commons/src/main/java/io/micrometer/common/KeyValue.java
+++ b/micrometer-commons/src/main/java/io/micrometer/common/KeyValue.java
@@ -28,6 +28,11 @@
  */
 public interface KeyValue extends Comparable<KeyValue> {
 
+    /**
+     * Use this if you want to indicate that the value is missing.
+     */
+    public static final String NONE = "none";
+
     String getKey();
 
     String getValue();