diff --git a/hlr/HLR_Tests.ttcn b/hlr/HLR_Tests.ttcn
index eca4f4b..8b21626 100644
--- a/hlr/HLR_Tests.ttcn
+++ b/hlr/HLR_Tests.ttcn
@@ -353,15 +353,28 @@
 
 
 testcase TC_gsup_sai_err_invalid_imsi() runs on test_CT {
-	var hexstring imsi := '01234'H;
+	/* 23.003 Section 2.2 clearly states that an IMSI with less
+	 * than 5 digits is impossible. Even 5 digits is still questionable */
+	var hexstring imsi := '0123'H;
 	var GSUP_PDU res;
 
 	f_init();
 
-	res := f_perform_SAI(imsi, 17);
+	res := f_perform_SAI(imsi, 96); /* Invalid Mandatory information */
 	setverdict(pass);
 }
 
+testcase TC_gsup_sai_err_unknown_imsi() runs on test_CT {
+	var hexstring imsi := f_rnd_imsi('26242'H);
+	var GSUP_PDU res;
+
+	f_init();
+
+	res := f_perform_SAI(imsi, 2);
+	setverdict(pass);
+}
+
+
 /* test SAI for a number of different subscriber cases (algo, 2g/3g, ...) */
 testcase TC_gsup_sai() runs on test_CT {
 	var HlrSubscriberList sl;
@@ -545,6 +558,7 @@
 	execute( TC_gsup_sai_err_invalid_imsi() );
 	execute( TC_gsup_sai() );
 	execute( TC_gsup_ul_unknown_imsi() );
+	execute( TC_gsup_sai_err_unknown_imsi() );
 	execute( TC_gsup_ul() );
 	execute( TC_vty() );
 	execute( TC_vty_msisdn_isd() );