diff --git a/src/csharp/generate_proto_csharp.sh b/src/csharp/generate_proto_csharp.sh
index a17f45b5874..f879e074aa5 100755
--- a/src/csharp/generate_proto_csharp.sh
+++ b/src/csharp/generate_proto_csharp.sh
@@ -42,7 +42,7 @@ $PROTOC --plugin=$PLUGIN --csharp_out=$EXAMPLES_DIR --grpc_out=$EXAMPLES_DIR \
     -I $EXAMPLES_DIR/proto $EXAMPLES_DIR/proto/math.proto
 
 $PROTOC --plugin=$PLUGIN --csharp_out=$INTEROP_DIR --grpc_out=$INTEROP_DIR \
-    -I $INTEROP_DIR/proto $INTEROP_DIR/proto/*.proto
+    -I ../.. ../../test/proto/*.proto
 
 $PROTOC --plugin=$PLUGIN --csharp_out=$HEALTHCHECK_DIR --grpc_out=$HEALTHCHECK_DIR \
     -I $HEALTHCHECK_DIR/proto $HEALTHCHECK_DIR/proto/health.proto