diff --git a/man/setDT.Rd b/man/setDT.Rd
index e45c7314c..4f352e996 100644
--- a/man/setDT.Rd
+++ b/man/setDT.Rd
@@ -8,12 +8,13 @@
   
 }
 \usage{
-setDT(x, keep.rownames=FALSE, key=NULL)
+setDT(x, keep.rownames=FALSE, key=NULL, check.names=FALSE)
 }
 \arguments{
   \item{x}{ A named or unnamed \code{list}, \code{data.frame} or \code{data.table}. }
   \item{keep.rownames}{ For \code{data.frame}s, \code{TRUE} retains the \code{data.frame}'s row names under a new column \code{rn}. }
   \item{key}{Character vector of one or more column names which is passed to \code{\link{setkeyv}}. It may be a single comma separated string such as \code{key="x,y,z"}, or a vector of names such as \code{key=c("x","y","z")}. }
+  \item{check.names}{ Just as \code{check.names} in \code{\link{data.frame}}. }
 }
 
 \details{
@@ -48,6 +49,11 @@ setDT(X, FALSE)
 # setkey directly
 X = list(a = 4:1, b=runif(4))
 setDT(X, key="a")[]
+
+# check.names argument
+X = list(a=1:5, a=6:10)
+setDT(X, check.names=TRUE)[]
+
 }
 \keyword{ data }