diff --git a/src/main/java/com/android/tools/r8/tracereferences/TraceReferencesCommand.java b/src/main/java/com/android/tools/r8/tracereferences/TraceReferencesCommand.java
index 1c98765..9aff1d0 100644
--- a/src/main/java/com/android/tools/r8/tracereferences/TraceReferencesCommand.java
+++ b/src/main/java/com/android/tools/r8/tracereferences/TraceReferencesCommand.java
@@ -114,6 +114,7 @@
     return printVersion;
   }
 
+  @Keep
   public static class Builder {
 
     private boolean printHelp = false;