diff --git a/core/api/src/main/java/org/onlab/onos/net/intent/constraint/LatencyConstraint.java b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/LatencyConstraint.java
index fcdf330..45151ef 100644
--- a/core/api/src/main/java/org/onlab/onos/net/intent/constraint/LatencyConstraint.java
+++ b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/LatencyConstraint.java
@@ -25,14 +25,13 @@
 import java.time.temporal.ChronoUnit;
 import java.util.Objects;
 
+import static org.onlab.onos.net.AnnotationKeys.LATENCY;
+
 /**
  * Constraint that evaluates the latency through a path.
  */
 public class LatencyConstraint implements Constraint {
 
-    // TODO: formalize the key for latency all over the codes.
-    private static final String LATENCY_KEY = "latency";
-
     private final Duration latency;
 
     /**
@@ -49,7 +48,7 @@
 
     @Override
     public double cost(Link link, LinkResourceService resourceService) {
-        String value = link.annotations().value(LATENCY_KEY);
+        String value = link.annotations().value(LATENCY);
 
         double latencyInMicroSec;
         try {