diff --git a/R/utils.R b/R/utils.R
index 4fc6b6cae9..a73f1d9c7b 100644
--- a/R/utils.R
+++ b/R/utils.R
@@ -67,9 +67,6 @@ if (inherits(rep_len(Sys.Date(), 1L), "Date")) {
   safe_rep_len = function(x, n) rep(x, length.out = n) # nolint: rep_len_linter.
 }
 
-# endsWith no longer used from #5097 so no need to backport; prevent usage to avoid dev delay until GLCI's R 3.1.0 test
-endsWith = function(...) internal_error("use endsWithAny instead of base::endsWith")
-
 startsWithAny = function(x,y) .Call(CstartsWithAny, x, y, TRUE)
 endsWithAny = function(x,y) .Call(CstartsWithAny, x, y, FALSE)
 # For fread.R #5097 we need if any of the prefixes match, which one, and can return early on the first match
diff --git a/inst/tests/tests.Rraw b/inst/tests/tests.Rraw
index 4277ed1533..5aa435cf07 100644
--- a/inst/tests/tests.Rraw
+++ b/inst/tests/tests.Rraw
@@ -42,7 +42,6 @@ if (exists("test.data.table", .GlobalEnv, inherits=FALSE)) {
   cube.data.table = data.table:::cube.data.table
   dcast.data.table = data.table:::dcast.data.table
   DTfun = data.table:::DT
-  endsWith = data.table:::endsWith
   endsWithAny = data.table:::endsWithAny
   forder = data.table:::forder
   forderv = data.table:::forderv
@@ -17316,7 +17315,6 @@ test(2194.6, endsWithAny(character(), 'a'), error="Internal error.*types or leng
 needed_chars = c("\u0105", "\u017E", "\u016B", "\u012F", "\u0173", "\u0117", "\u0161", "\u0119")
 txt = parse(text='readLines(testDir("issue_563_fread.txt"))')
 test(2194.7, requires_utf8=needed_chars, endsWithAny(eval(txt), 'B'), error="Internal error.*types or lengths incorrect") # txt is length 5
-test(2194.8, endsWith('abcd', 'd'), error="Internal error.*use endsWithAny")
 
 # uniqueN(x, by=character()) was internal error, #4594
 DT = data.table(idx=c(1L,2L,1L,3L), value="val")
diff --git a/src/data.table.h b/src/data.table.h
index 4c4d112df0..7e815de471 100644
--- a/src/data.table.h
+++ b/src/data.table.h
@@ -2,17 +2,6 @@
 #include "dt_stdio.h"  // PRId64 and PRIu64
 #include <R.h>
 #include <Rversion.h>
-#if R_VERSION < R_Version(3, 5, 0)  // R-exts$6.14
-#  define ALTREP(x) 0     // #2866
-#  define USE_RINTERNALS  // #3301
-#  define DATAPTR_RO(x) ((const void *)DATAPTR(x))
-#  define STRING_PTR_RO STRING_PTR
-#  define INTEGER_RO INTEGER
-#  define REAL_RO REAL
-#  define COMPLEX_RO COMPLEX
-#  define RAW_RO RAW
-#  define LOGICAL_RO LOGICAL
-#endif
 #if R_VERSION < R_Version(4, 5, 0)
 #  define R_getVar(x, env, inherits) findVar(x, env)
 #  define isDataFrame(x) isFrame(x) // #6180