diff --git a/R/print.data.table.R b/R/print.data.table.R
index d53855d79d..96f3e8060c 100644
--- a/R/print.data.table.R
+++ b/R/print.data.table.R
@@ -15,6 +15,8 @@ print.data.table = function(x, topn=getOption("datatable.print.topn"),
   # trunc.cols - should only the columns be printed that can fit in the console? (FALSE)
   if (!col.names %chin% c("auto", "top", "none"))
     stop("Valid options for col.names are 'auto', 'top', and 'none'")
+  if (length(trunc.cols) != 1L || !is.logical(trunc.cols) || is.na(trunc.cols))
+    stop("Valid options for trunc.cols are TRUE and FALSE")
   if (col.names == "none" && class)
     warning("Column classes will be suppressed when col.names is 'none'")
   if (!shouldPrint(x)) {
diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
index ef23279700..88465242c7 100644
--- a/inst/tests/tests.Rraw
+++ b/inst/tests/tests.Rraw
@@ -17319,3 +17319,10 @@ if (identical(text, enc2native(text))) { # ensure native encoding can represent
 }
 test(2167.3, fwrite(dt, csvfile, encoding="nativ"), error="Argument 'encoding' must be")
 unlink(csvfile)
+
+# check valid trunc.cols=, #4766
+DT = data.table(x = rnorm(10))
+test(2168.01, print(DT, trunc.cols = 5L), error=c("Valid options for trunc.cols are TRUE and FALSE"))
+test(2168.02, print(DT, trunc.cols = NA), error=c("Valid options for trunc.cols are TRUE and FALSE"))
+test(2168.03, print(DT, trunc.cols = "thing"), error=c("Valid options for trunc.cols are TRUE and FALSE"))
+test(2168.04, print(DT, trunc.cols = c(TRUE, FALSE)), error=c("Valid options for trunc.cols are TRUE and FALSE"))