diff --git a/pkg/ueps/packet_test.go b/pkg/ueps/packet_test.go
index 2b15a54..8798e92 100644
--- a/pkg/ueps/packet_test.go
+++ b/pkg/ueps/packet_test.go
@@ -38,8 +38,9 @@ func TestPacket_NewPacketBuilder_Good(t *testing.T) {
 }
 
 // builder := NewPacketBuilder(0x04, nil)
-// frame, err := builder.MarshalAndSign(secret) // succeeds with zero-length payload
+// frame, err := builder.MarshalAndSign([]byte("shared-secret")) // succeeds with zero-length payload
 func TestPacket_NewPacketBuilder_Bad(t *testing.T) {
+	sharedSecret := []byte("shared-secret")
 	builder := NewPacketBuilder(0x04, nil)
 
 	if builder == nil {
@@ -49,7 +50,7 @@ func TestPacket_NewPacketBuilder_Bad(t *testing.T) {
 		t.Errorf("expected nil Payload, got %v", builder.Payload)
 	}
 
-	frame, err := builder.MarshalAndSign([]byte("secret"))
+	frame, err := builder.MarshalAndSign(sharedSecret)
 	if err != nil {
 		t.Fatalf("MarshalAndSign with nil payload failed: %v", err)
 	}
@@ -59,8 +60,9 @@ func TestPacket_NewPacketBuilder_Bad(t *testing.T) {
 }
 
 // builder := NewPacketBuilder(0x00, largePayload)
-// frame, err := builder.MarshalAndSign(secret) // succeeds; 0xFF tag appended without length prefix
+// frame, err := builder.MarshalAndSign([]byte("shared-secret")) // succeeds; 0xFF tag appended without length prefix
 func TestPacket_NewPacketBuilder_Ugly(t *testing.T) {
+	sharedSecret := []byte("shared-secret")
 	largePayload := bytes.Repeat([]byte("x"), 300)
 	builder := NewPacketBuilder(0x00, largePayload)
 
@@ -68,7 +70,7 @@ func TestPacket_NewPacketBuilder_Ugly(t *testing.T) {
 		t.Errorf("expected IntentID 0x00, got 0x%02x", builder.Header.IntentID)
 	}
 
-	frame, err := builder.MarshalAndSign([]byte("secret"))
+	frame, err := builder.MarshalAndSign(sharedSecret)
 	if err != nil {
 		t.Fatalf("MarshalAndSign with 300-byte payload failed: %v", err)
 	}