diff --git a/modern/src/runtime/System.ts b/modern/src/runtime/System.ts
index 7e4e1ccb..c5180201 100644
--- a/modern/src/runtime/System.ts
+++ b/modern/src/runtime/System.ts
@@ -449,7 +449,7 @@ class System extends MakiObject {
   // returns the datetime's year since 1900
   getdateyear(datetime: number): number {
     const date = new Date(datetime * 1000);
-    return date.getYear();
+    return date.getFullYear() - 1900;
   }
 
   // returns the datetime's month (0-11)