diff --git a/R/data.table.R b/R/data.table.R
index 424dcddb55..a1e91ae814 100644
--- a/R/data.table.R
+++ b/R/data.table.R
@@ -137,7 +137,10 @@ print.data.table <- function(x,
 is.formula <- function(x) class(x) == "formula"
 
 format.data.table <- function (x, ..., justify="none") {
-    format.item <- function(x) {
+    if (is.atomic(x) && !is.null(x)) {
+        stop("Internal structure doesn't seem to be a list. Possibly corrupt data.table.")
+    }
+     format.item <- function(x) {
         if (is.atomic(x) || is.formula(x)) # FR #2591 - format.data.table issue with columns of class "formula"
             paste(c(format(head(x,6), justify=justify, ...), if(length(x)>6)""),collapse=",")  # fix for #5435 - format has to be added here...
         else
diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
index 03eb94ced0..3e04e2706a 100644
--- a/inst/tests/tests.Rraw
+++ b/inst/tests/tests.Rraw
@@ -5982,7 +5982,11 @@ test(1486.2, as.data.frame(ans2.1), as.data.frame(ans2.1))
 # Fix for #832
 x <- matrix(1:9, ncol=3)
 setattr(x, "names", paste("V", seq_len(length(x)), sep = ""))
-test(1486.3, setattr(x, "class", c("data.table", "data.frame")), error="Internal structure doesn't seem to be a list")
+test(1487.1, setattr(x, "class", c("data.table", "data.frame")), error="Internal structure doesn't seem to be a list")
+x <- matrix(1:9, ncol=3)
+class(x) = c("data.table", "data.frame")
+# not sure how to test this one, so using `tryCatch`
+test(1487.2, tryCatch(print(x), error=function(k) "bla"), "bla")
 
 ##########################