diff --git a/cli/qmicli-nas.c b/cli/qmicli-nas.c
index 3474929..73e4aed 100644
--- a/cli/qmicli-nas.c
+++ b/cli/qmicli-nas.c
@@ -1098,7 +1098,7 @@ get_system_info_ready (QmiClientNas *client,
                     g_print ("\t\tPacket zone: '%" G_GUINT16_FORMAT "'\n", packet_zone);
                 if (network_id_valid) {
                     g_print ("\t\tMCC: '%s'\n", mcc);
-                    if (mnc[2] == 0xFF)
+                    if ((guchar)mnc[2] == 0xFF)
                         g_print ("\t\tMNC: '%.2s'\n", mnc);
                     else
                         g_print ("\t\tMNC: '%.3s'\n", mnc);
@@ -1268,7 +1268,7 @@ get_system_info_ready (QmiClientNas *client,
                              registration_reject_cause);
                 if (network_id_valid) {
                     g_print ("\t\tMCC: '%s'\n", mcc);
-                    if (mnc[2] == 0xFF)
+                    if ((guchar)mnc[2] == 0xFF)
                         g_print ("\t\tMNC: '%.2s'\n", mnc);
                     else
                         g_print ("\t\tMNC: '%.3s'\n", mnc);
@@ -1388,7 +1388,7 @@ get_system_info_ready (QmiClientNas *client,
                              registration_reject_cause);
                 if (network_id_valid) {
                     g_print ("\t\tMCC: '%s'\n", mcc);
-                    if (mnc[2] == 0xFF)
+                    if ((guchar)mnc[2] == 0xFF)
                         g_print ("\t\tMNC: '%.2s'\n", mnc);
                     else
                         g_print ("\t\tMNC: '%.3s'\n", mnc);
@@ -1502,7 +1502,7 @@ get_system_info_ready (QmiClientNas *client,
                              registration_reject_cause);
                 if (network_id_valid) {
                     g_print ("\t\tMCC: '%s'\n", mcc);
-                    if (mnc[2] == 0xFF)
+                    if ((guchar)mnc[2] == 0xFF)
                         g_print ("\t\tMNC: '%.2s'\n", mnc);
                     else
                         g_print ("\t\tMNC: '%.3s'\n", mnc);
@@ -1623,7 +1623,7 @@ get_system_info_ready (QmiClientNas *client,
                              registration_reject_cause);
                 if (network_id_valid) {
                     g_print ("\t\tMCC: '%s'\n", mcc);
-                    if (mnc[2] == 0xFF)
+                    if ((guchar)mnc[2] == 0xFF)
                         g_print ("\t\tMNC: '%.2s'\n", mnc);
                     else
                         g_print ("\t\tMNC: '%.3s'\n", mnc);