diff --git a/functions.h b/functions.h
--- a/functions.h
+++ b/functions.h
@@ -167,8 +167,6 @@ StringID RealAllocateName(const char *na
 void ConvertDayToYMD(YearMonthDay *ymd, uint16 date);
 uint ConvertYMDToDay(uint year, uint month, uint day);
 uint ConvertIntDate(uint date);
-void CSleep(int milliseconds);
-
 
 /* misc functions */
 void MarkTileDirty(int x, int y);