diff --git a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ProgramCounter.java b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ProgramCounter.java
index b6db8e7..a59ddf5 100644
--- a/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ProgramCounter.java
+++ b/apps/workflow/api/src/main/java/org/onosproject/workflow/api/ProgramCounter.java
@@ -29,12 +29,12 @@
     /**
      * index of the worklet.
      */
-    private int workletIndex;
+    private final int workletIndex;
 
     /**
      * Type of worklet.
      */
-    private String workletType;
+    private final String workletType;
 
     /**
      * Index of worklet.