diff --git a/R/data.table.R b/R/data.table.R
index af4f14de0..e3dfea13e 100644
--- a/R/data.table.R
+++ b/R/data.table.R
@@ -2703,7 +2703,8 @@ setDT = function(x, keep.rownames=FALSE, key=NULL, check.names=FALSE) {
       x[, (nm[1L]) := rn]
       setcolorder(x, nm)
     }
-  } else if (is.list(x) && length(x)==1L && is.matrix(x[[1L]])) {
+  } 
+  if (is.list(x) && length(x)==1L && is.matrix(x[[1L]])) {
     # a single list(matrix) is unambiguous and depended on by some revdeps, #3581
     x = as.data.table.matrix(x[[1L]])
   } else if (is.null(x) || (is.list(x) && !length(x))) {