diff --git a/src/mms/iso_server/iso_server.c b/src/mms/iso_server/iso_server.c
index 8fa498b4..62c43ebb 100644
--- a/src/mms/iso_server/iso_server.c
+++ b/src/mms/iso_server/iso_server.c
@@ -440,6 +440,11 @@ setupIsoServer(IsoServer self)
             CONFIG_TCP_KEEPALIVE_CNT);
 #endif
 
+#if (CONFIG_MAXIMUM_TCP_CLIENT_CONNECTIONS == -1)
+    if (self->openClientConnections == NULL)
+        self->openClientConnections = LinkedList_create();
+#endif
+
     ServerSocket_setBacklog((ServerSocket) self->serverSocket, BACKLOG);
 
     ServerSocket_listen((ServerSocket) self->serverSocket);
@@ -667,6 +672,11 @@ IsoServer_startListening(IsoServer self)
 
     self->state = ISO_SVR_STATE_IDLE;
 
+#if (CONFIG_MAXIMUM_TCP_CLIENT_CONNECTIONS == -1)
+    if (self->openClientConnections == NULL)
+        self->openClientConnections = LinkedList_create();
+#endif
+
     self->serverThread = Thread_create((ThreadExecutionFunction) isoServerThread, self, false);
 
     Thread_start(self->serverThread);