diff --git a/src/library/base/R/datetime.R b/src/library/base/R/datetime.R
index 95e513f..67cbea2 100644
--- a/src/library/base/R/datetime.R
+++ b/src/library/base/R/datetime.R
@@ -729,7 +729,7 @@ cut.POSIXt <-
         end <- as.POSIXlt(max(x, na.rm = TRUE))
         end <- as.POSIXlt(end + (31 * 86400))
         end$mday <- 1
-        breaks <- seq(start, end, "months")
+        breaks <- seq(start, end, breaks)
     } else if(valid == 7) {
         start$mon <- 0
         start$mday <- 1
@@ -737,7 +737,7 @@ cut.POSIXt <-
         end <- as.POSIXlt(end + (366 * 86400))
         end$mon <- 0
         end$mday <- 1
-        breaks <- seq(start, end, "years")
+        breaks <- seq(start, end, breaks)
     } else {
         if (length(by2) == 2) incr <- incr * as.integer(by2[1])
 	    maxx <- max(x, na.rm = TRUE)
