diff --git a/tests/tbf/TbfTest.cpp b/tests/tbf/TbfTest.cpp
index 80bc818..19895ad 100644
--- a/tests/tbf/TbfTest.cpp
+++ b/tests/tbf/TbfTest.cpp
@@ -388,18 +388,23 @@
 	OSMO_ASSERT(ms1 == ms2);
 
 	/* use the same IMSI on TBF 2 */
-	dl_tbf[1]->assign_imsi("001001000000002");
-	ms1 = the_bts.ms_store().get_ms(0, 0, "001001000000002");
-	OSMO_ASSERT(ms1 != NULL);
-	OSMO_ASSERT(ms1 != ms2);
-	OSMO_ASSERT(strcmp(ms1->imsi(), "001001000000002") == 0);
-	OSMO_ASSERT(strcmp(ms2->imsi(), "") == 0);
+	{
+		GprsMs::Guard guard(ms2);
+		dl_tbf[1]->assign_imsi("001001000000002");
+		ms1 = the_bts.ms_store().get_ms(0, 0, "001001000000002");
+		OSMO_ASSERT(ms1 != NULL);
+		OSMO_ASSERT(ms1 != ms2);
+		OSMO_ASSERT(strcmp(ms1->imsi(), "001001000000002") == 0);
+		OSMO_ASSERT(strcmp(ms2->imsi(), "") == 0);
+	}
+
+	ms2 = the_bts.ms_store().get_ms(0xf1000001);
+	OSMO_ASSERT(ms2 == NULL);
 
 	tbf_free(dl_tbf[1]);
 	ms1 = the_bts.ms_store().get_ms(0, 0, "001001000000002");
 	OSMO_ASSERT(ms1 == NULL);
 
-	tbf_free(dl_tbf[0]);
 	printf("=== end %s ===\n", __func__);
 }
 
diff --git a/tests/tbf/TbfTest.err b/tests/tbf/TbfTest.err
index 099504f..3524522 100644
--- a/tests/tbf/TbfTest.err
+++ b/tests/tbf/TbfTest.err
@@ -462,19 +462,20 @@
 Modifying MS object, TLLI = 0xf1000001, IMSI '' -> '001001000000001'
 Modifying MS object, TLLI = 0xf1000001, IMSI '001001000000001' -> '001001000000002'
 TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW) the IMSI '001001000000002' was already assigned to another MS object: TLLI = 0xf1000001, that IMSI will be removed
-Modifying MS object, TLLI = 0xf1000001, IMSI '001001000000002' -> ''
 Modifying MS object, TLLI = 0xf1000002, IMSI '' -> '001001000000002'
-TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW) free
-TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW) Software error: Pending downlink assignment. This may not happen, because the assignment message never gets transmitted. Please be sure not to free in this state. PLEASE FIX!
-PDCH(TS 4, TRX 0): Detaching TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW), 1 TBFs, USFs = 00, TFIs = 00000001.
-Detaching TBF from MS object, TLLI = 0xf1000002, TBF = TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW)
-Destroying MS object, TLLI = 0xf1000002
-********** TBF ends here **********
+Modifying MS object, TLLI = 0xf1000001, IMSI '001001000000002' -> ''
 TBF(TFI=0 TLLI=0xf1000001 DIR=DL STATE=FLOW) free
 TBF(TFI=0 TLLI=0xf1000001 DIR=DL STATE=FLOW) Software error: Pending downlink assignment. This may not happen, because the assignment message never gets transmitted. Please be sure not to free in this state. PLEASE FIX!
-PDCH(TS 4, TRX 0): Detaching TBF(TFI=0 TLLI=0xf1000001 DIR=DL STATE=FLOW), 0 TBFs, USFs = 00, TFIs = 00000000.
+PDCH(TS 4, TRX 0): Detaching TBF(TFI=0 TLLI=0xf1000001 DIR=DL STATE=FLOW), 1 TBFs, USFs = 00, TFIs = 00000002.
 Detaching TBF from MS object, TLLI = 0xf1000001, TBF = TBF(TFI=0 TLLI=0xf1000001 DIR=DL STATE=FLOW)
-Destroying MS object, TLLI = 0xf1000001
+********** TBF ends here **********
+Clearing MS object, TLLI: 0xf1000001, IMSI: ''
+Destroying MS object, TLLI = 0x00000000
+TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW) free
+TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW) Software error: Pending downlink assignment. This may not happen, because the assignment message never gets transmitted. Please be sure not to free in this state. PLEASE FIX!
+PDCH(TS 4, TRX 0): Detaching TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW), 0 TBFs, USFs = 00, TFIs = 00000000.
+Detaching TBF from MS object, TLLI = 0xf1000002, TBF = TBF(TFI=1 TLLI=0xf1000002 DIR=DL STATE=FLOW)
+Destroying MS object, TLLI = 0xf1000002
 ********** TBF ends here **********
 ********** TBF starts here **********
 Allocating DL TBF: MS_CLASS=45