diff --git a/NEWS.md b/NEWS.md
index 596a01f7d6..63bf10d094 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -86,6 +86,8 @@
 
 14. Filling columns of class Date with POSIXct (and vice versa) using `shift()` now yields a clear, informative error message specifying the class mismatch, [#5218](https://github.com/Rdatatable/data.table/issues/5218). Thanks @ashbaldry for the report and @ben-schwen for the fix.
 
+15. `dim.data.table` returns now the same as `dim.data.frame` in `data.table`-unaware environments, [#2422](https://github.com/Rdatatable/data.table/issues/2422). Thanks to @akersting for reporting and Benjamin Schwendinger for the fix.
+
 ### NOTES
 
 1. The following in-progress deprecations have proceeded:
diff --git a/R/cedta.R b/R/cedta.R
index 6c99bea302..4528578298 100644
--- a/R/cedta.R
+++ b/R/cedta.R
@@ -48,7 +48,7 @@ cedta.pkgEvalsUserCode = c("gWidgetsWWW","statET","FastRWeb","slidify","rmarkdow
 }
 
 # cedta = Calling Environment Data.Table-Aware
-cedta = function(n=2L) {
+cedta = function(n=2L, verbose = getOption("datatable.verbose", FALSE)) {
   # Calling Environment Data Table Aware
   env = parent.frame(n)
   if (isTRUEorFALSE(env$.datatable.aware)) { # dtplyr#184, #5654
@@ -72,7 +72,7 @@ cedta = function(n=2L) {
     (nsname %chin% cedta.pkgEvalsUserCode && .any_eval_calls_in_stack()) ||
     isTRUE(ns$.datatable.aware) ||  # As of Sep 2018: RCAS, caretEnsemble, dtplyr, rstanarm, rbokeh, CEMiTool, rqdatatable, RImmPort, BPRMeth, rlist
     tryCatch("data.table" %chin% get(".Depends",paste("package",nsname,sep=":"),inherits=FALSE),error=function(e)FALSE)  # both ns$.Depends and get(.Depends,ns) are not sufficient
-  if (!ans && getOption("datatable.verbose")) {
+  if (!ans && verbose) {
     # nocov start
     catf("cedta decided '%s' wasn't data.table aware. Here is call stack with [[1L]] applied:\n", nsname)
     print(sapply(sys.calls(), `[[`, 1L))
diff --git a/R/data.table.R b/R/data.table.R
index 5702558409..198f8b0d89 100644
--- a/R/data.table.R
+++ b/R/data.table.R
@@ -1,5 +1,6 @@
 dim.data.table = function(x)
 {
+  if (!cedta(verbose=FALSE)) return(NextMethod()) # nocov
   .Call(Cdim, x)
 }
 
diff --git a/R/print.data.table.R b/R/print.data.table.R
index 1504b32341..03e0fe3f8f 100644
--- a/R/print.data.table.R
+++ b/R/print.data.table.R
@@ -72,7 +72,7 @@ print.data.table = function(x, topn=getOption("datatable.print.topn"),
       setnames(index_dt, print_names)
     }
   }
-  n_x = nrow(x)
+  n_x = dim(x)[1L] # manually dispatch nrow() to avoid dispatching to S3 method
   if ((topn*2L+1L)<n_x && (n_x>nrows || !topnmiss)) {
     toprint = rbindlist(list(head(x, topn), tail(x, topn)), use.names=FALSE)  # no need to match names because head and tail of same x, and #3306
     rn = c(seq_len(topn), seq.int(to=n_x, length.out=topn))