--- datetime.R	2011-04-22 13:04:29.000000000 -0500
+++ datetime.R.new	2011-04-22 13:18:10.000000000 -0500
@@ -237,6 +237,8 @@
     force(xlab)
     incr <- 1
     ## handle breaks ourselves
+    if(missing(breaks))
+	stop("Must specify 'breaks' in hist(<Date>)")    
     if (inherits(breaks, "Date")) {
         breaks <- as.Date(breaks)
         d <- min(abs(diff(unclass(breaks))))