diff --git a/stream/mts/psi/psi_test.go b/stream/mts/psi/psi_test.go
index 0397bc33..96d9f5d5 100644
--- a/stream/mts/psi/psi_test.go
+++ b/stream/mts/psi/psi_test.go
@@ -34,7 +34,7 @@ import (
 // Some common manifestations of PSI
 var (
 	// PSI struct to represent basic pat
-	StandardPat = PSI{
+	standardPat = PSI{
 		Pf:  0x00,
 		Tid: 0x00,
 		Ssi: true,
@@ -54,7 +54,7 @@ var (
 	}
 
 	// PSI struct to represent basic pmt without descriptors for time and location
-	StandardPmt = PSI{
+	standardPmt = PSI{
 		Pf:  0x00,
 		Tid: 0x02,
 		Ssi: true,
@@ -78,7 +78,7 @@ var (
 	}
 
 	// Std pmt with time and location descriptors, time and location fields are zeroed out
-	StandardPmtTimeLocation = PSI{
+	standardPmtTimeLocation = PSI{
 		Pf:  0x00,
 		Tid: 0x02,
 		Ssi: true,