--- modem-manager-gui-0.0.19.1/src/strformat.c.old	2019-06-03 17:33:59.349304793 +0500
+++ modem-manager-gui-0.0.19.1/src/strformat.c	2019-06-03 17:38:26.586850540 +0500
@@ -181,8 +181,10 @@
 	ftime = localtime(&timestamp);
 		
 	memset(buffer, 0, bufsize);
-	
-	if (delta <= 0.0) {
+
+        if (delta <= -86400.0) {
+                g_snprintf(buffer, bufsize, _("Unknown"));
+        } else if (delta <= 0.0) {
 		if (strftime(buffer, bufsize, _("Today, %T"), ftime) == 0) {
 			g_snprintf(buffer, bufsize, _("Unknown"));
 		}