diff --git a/gtests/net/packetdrill/parser.y b/gtests/net/packetdrill/parser.y
index e0e4fdc5389bcb7c69ca2d67705085c3687530e1..51843f8d1efe7a8c3367c671f90a7fb9f44d6b75 100644
--- a/gtests/net/packetdrill/parser.y
+++ b/gtests/net/packetdrill/parser.y
@@ -1634,7 +1634,7 @@ i_forward_tsn_id
 	if (!is_valid_u16($2)) {
 		semantic_error("stream identifier out of range");
 	}
-        if (!is_valid_u16($4)) {
+	if (!is_valid_u16($4)) {
 		semantic_error("reserved out of range");
 	}
 	if (!is_valid_u32($6)) {