diff --git a/p4/README.md b/p4/README.md
index 757b2deb7da413d35f0ebada7501fac9eb2797fe..538817a3ab3e148ea16e50fe5948c12315054286 100644
--- a/p4/README.md
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@@ -124,6 +124,8 @@ The documents [here](https://hadoop.apache.org/docs/r3.3.6/hadoop-project-dist/h
 
 Use a `GETFILEBLOCKLOCATIONS` operation to find the block locations.
 
+**Hint:** You have to set appropriate environment variable `CLASSPATH` to access HDFS correctly. See example [here](https://git.doit.wisc.edu/cdis/cs/courses/cs544/s25/main/-/blob/main/lec/18-hdfs/notebook.Dockerfile?ref_type=heads).          
+
 ## Part 3: `CalcAvgLoan` gRPC Call
 
 In this part, your task is to implement the `CalcAvgLoan` gRPC call (you can find the interface definition in the proto file).