diff --git a/core/src/com/google/inject/Key.java b/core/src/com/google/inject/Key.java
index 79389c41f3..c12b4f29b4 100644
--- a/core/src/com/google/inject/Key.java
+++ b/core/src/com/google/inject/Key.java
@@ -21,6 +21,7 @@
 import static com.google.inject.internal.Annotations.generateAnnotation;
 import static com.google.inject.internal.Annotations.isAllDefaultMethods;
 
+import com.google.errorprone.annotations.CheckReturnValue;
 import com.google.inject.internal.Annotations;
 import com.google.inject.internal.MoreTypes;
 import java.lang.annotation.Annotation;
@@ -47,6 +48,7 @@
  *
  * @author crazybob@google.com (Bob Lee)
  */
+@CheckReturnValue
 public class Key<T> {
 
   private final AnnotationStrategy annotationStrategy;