XER reference types encoding error

diff --git a/tests/37-indirect-choice-OK.asn1.-EF b/tests/37-indirect-choice-OK.asn1.-EF
index 8966815..b4031a8 100644
--- a/tests/37-indirect-choice-OK.asn1.-EF
+++ b/tests/37-indirect-choice-OK.asn1.-EF
@@ -24,4 +24,10 @@
 
 Choice3 ::= [3] EXPLICIT Choice2
 
+Choice4 ::= [4] IMPLICIT Choice2
+
+Choice5 ::= Choice2
+
+Choice6 ::= Choice1
+
 END