diff -ura pdfpc-4.1.2.orig/src/classes/timer_label.vala pdfpc-4.1.2.new/src/classes/timer_label.vala
--- pdfpc-4.1.2.orig/src/classes/timer_label.vala	2018-08-22 16:32:38.500386644 -0300
+++ pdfpc-4.1.2.new/src/classes/timer_label.vala	2018-08-22 16:33:30.163549315 -0300
@@ -204,14 +204,7 @@
             minutes = timeInSecs / 60 % 60;
             seconds = timeInSecs % 60 % 60;
 
-            this.set_text(
-                "%s%.2u:%.2u:%.2u".printf(
-                    prefix,
-                    hours,
-                    minutes,
-                    seconds
-                )
-            );
+            this.set_text("");
         }
     }