diff --git a/src/main/scala/li/cil/oc/util/GameTimeFormatter.scala b/src/main/scala/li/cil/oc/util/GameTimeFormatter.scala
index d21eb631c..54fdaca60 100644
--- a/src/main/scala/li/cil/oc/util/GameTimeFormatter.scala
+++ b/src/main/scala/li/cil/oc/util/GameTimeFormatter.scala
@@ -31,7 +31,7 @@ object GameTimeFormatter {
     //'G' -> (t => ""),
     'h' -> (t => format("%b", t)),
     'H' -> (t => "%02d".format(t.hour)),
-    'I' -> (t => "%02d".format(t.hour % 12 + 1)),
+    'I' -> (t => "%02d".format((t.hour + 11) % 12 + 1)),
     'j' -> (t => "%03d".format(t.yearDay)),
     'm' -> (t => "%02d".format(t.month)),
     'M' -> (t => "%02d".format(t.minute)),