diff --git a/library/Osmocom_Gb_Types.ttcn b/library/Osmocom_Gb_Types.ttcn
index 2afedcc4a..ba05f7db0 100644
--- a/library/Osmocom_Gb_Types.ttcn
+++ b/library/Osmocom_Gb_Types.ttcn
@@ -1255,7 +1255,7 @@ octetstring sdu) := {
 				iEI := '1E'O,
 				ext := '1'B,
 				lengthIndicator := {
-					length1 := 2
+					length1 := 1
 				},
 				unstructured_Value := tag
 			}