diff --git a/examples/server_example3/server_example3.c b/examples/server_example3/server_example3.c
index 2dfa2fc..b5f6e0b 100644
--- a/examples/server_example3/server_example3.c
+++ b/examples/server_example3/server_example3.c
@@ -129,14 +129,26 @@ main(int argc, char** argv)
 
         IedServer_lockDataModel(iedServer);
 
+        Timestamp iecTimestamp;
+
+        Timestamp_clearFlags(&iecTimestamp);
+        Timestamp_setTimeInMilliseconds(&iecTimestamp, timestamp);
+
+        /* toggle clock-not-synchronized flag in timestamp */
+        if (((int) t % 2) == 0)
+            Timestamp_setClockNotSynchronized(&iecTimestamp, true);
+
         IedServer_updateFloatAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn1_mag_f, an1);
-        IedServer_updateUTCTimeAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn1_t, timestamp);
+        IedServer_updateTimestampAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn1_t, &iecTimestamp);
+
         IedServer_updateFloatAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn2_mag_f, an2);
-        IedServer_updateUTCTimeAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn2_t, timestamp);
+        IedServer_updateTimestampAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn2_t, &iecTimestamp);
+
         IedServer_updateFloatAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn3_mag_f, an3);
-        IedServer_updateUTCTimeAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn3_t, timestamp);
+        IedServer_updateTimestampAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn3_t, &iecTimestamp);
+
         IedServer_updateFloatAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn4_mag_f, an4);
-        IedServer_updateUTCTimeAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn4_t, timestamp);
+        IedServer_updateTimestampAttributeValue(iedServer, IEDMODEL_GenericIO_GGIO1_AnIn4_t, &iecTimestamp);
 
         IedServer_unlockDataModel(iedServer);
 
diff --git a/src/iec61850/server/mms_mapping/mms_mapping.c b/src/iec61850/server/mms_mapping/mms_mapping.c
index feeca50..ac4bee6 100644
--- a/src/iec61850/server/mms_mapping/mms_mapping.c
+++ b/src/iec61850/server/mms_mapping/mms_mapping.c
@@ -2156,10 +2156,13 @@ mmsReadAccessHandler (void* parameter, MmsDomain* domain, char* variableId, MmsS
     if (DEBUG_IED_SERVER)
         printf("IED_SERVER: mmsReadAccessHandler: Requested %s\n", variableId);
 
-#if (CONFIG_IEC61850_SETTING_GROUPS == 1)
-
     char* separator = strchr(variableId, '$');
 
+    if (separator == NULL)
+        return DATA_ACCESS_ERROR_SUCCESS;
+
+#if (CONFIG_IEC61850_SETTING_GROUPS == 1)
+
     if (isFunctionalConstraintSE(separator)) {
         SettingGroup* sg = getSettingGroupByMmsDomain(self, domain);
 
diff --git a/src/mms/iso_cotp/cotp.c b/src/mms/iso_cotp/cotp.c
index 10c24c4..4d53f77 100644
--- a/src/mms/iso_cotp/cotp.c
+++ b/src/mms/iso_cotp/cotp.c
@@ -577,7 +577,13 @@ parseCotpMessage(CotpConnection* self)
     uint8_t tpduType;
 
     len = buffer[0];
-    assert(len <= tpduLength);
+
+    if (len > tpduLength) {
+      if (DEBUG_COTP)
+          printf("COTP: parseCotpMessage: len=%d tpduLength=%d\n", len, tpduLength);
+
+      return COTP_ERROR;
+    }
 
     tpduType = buffer[1];