diff --git a/extra/calendar/holidays/us/us.factor b/extra/calendar/holidays/us/us.factor
index f60f2163c2..7b3a7ea570 100644
--- a/extra/calendar/holidays/us/us.factor
+++ b/extra/calendar/holidays/us/us.factor
@@ -16,7 +16,7 @@ SYNTAX: us-federal
     january 3 monday-of-month ; us-federal
 
 : inauguration-day ( timestamp/n -- timestamp )
-    year dup 4 mod + january 20 >>day ; us-federal
+    year dup neg 4 rem + january 20 >>day ; us-federal
 
 : washington's-birthday ( timestamp/n -- timestamp )
     february 3 monday-of-month ; us-federal