diff --git a/Lib/test/support/script_helper.py b/Lib/test/support/script_helper.py
index 9c2e9ebdfba..c45d010a718 100644
--- a/Lib/test/support/script_helper.py
+++ b/Lib/test/support/script_helper.py
@@ -73,6 +73,10 @@ def run_python_until_end(*args, **env_vars):
     # Need to preserve the original environment, for in-place testing of
     # shared library builds.
     env = os.environ.copy()
+    # set TERM='' unless the TERM environment variable is passed explicitly
+    # see issues #11390 and #18300
+    if 'TERM' not in env_vars:
+        env['TERM'] = ''
     # But a special flag that can be set to override -- in this case, the
     # caller is responsible to pass the full environment.
     if env_vars.pop('__cleanenv', None):
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 29426a31853..33163b93879 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -2719,12 +2719,6 @@ output into something we can doctest against:
     >>> def normalize(s):
     ...     return '\n'.join(s.decode().splitlines())
 
-Note: we also pass TERM='' to all the assert_python calls to avoid a bug
-in the readline library that is triggered in these tests because we are
-running them in a new python process.  See:
-
-  http://lists.gnu.org/archive/html/bug-readline/2013-06/msg00000.html
-
 With those preliminaries out of the way, we'll start with a file with two
 simple tests and no errors.  We'll run both the unadorned doctest command, and
 the verbose version, and then check the output:
@@ -2741,9 +2735,9 @@ the verbose version, and then check the output:
     ...         _ = f.write('\n')
     ...         _ = f.write('And that is it.\n')
     ...     rc1, out1, err1 = script_helper.assert_python_ok(
-    ...             '-m', 'doctest', fn, TERM='')
+    ...             '-m', 'doctest', fn)
     ...     rc2, out2, err2 = script_helper.assert_python_ok(
-    ...             '-m', 'doctest', '-v', fn, TERM='')
+    ...             '-m', 'doctest', '-v', fn)
 
 With no arguments and passing tests, we should get no output:
 
@@ -2806,17 +2800,17 @@ text files).
     ...         _ = f.write('   \"\"\"\n')
     ...     import shutil
     ...     rc1, out1, err1 = script_helper.assert_python_failure(
-    ...             '-m', 'doctest', fn, fn2, TERM='')
+    ...             '-m', 'doctest', fn, fn2)
     ...     rc2, out2, err2 = script_helper.assert_python_ok(
-    ...             '-m', 'doctest', '-o', 'ELLIPSIS', fn, TERM='')
+    ...             '-m', 'doctest', '-o', 'ELLIPSIS', fn)
     ...     rc3, out3, err3 = script_helper.assert_python_ok(
     ...             '-m', 'doctest', '-o', 'ELLIPSIS',
-    ...             '-o', 'NORMALIZE_WHITESPACE', fn, fn2, TERM='')
+    ...             '-o', 'NORMALIZE_WHITESPACE', fn, fn2)
     ...     rc4, out4, err4 = script_helper.assert_python_failure(
-    ...             '-m', 'doctest', '-f', fn, fn2, TERM='')
+    ...             '-m', 'doctest', '-f', fn, fn2)
     ...     rc5, out5, err5 = script_helper.assert_python_ok(
     ...             '-m', 'doctest', '-v', '-o', 'ELLIPSIS',
-    ...             '-o', 'NORMALIZE_WHITESPACE', fn, fn2, TERM='')
+    ...             '-o', 'NORMALIZE_WHITESPACE', fn, fn2)
 
 Our first test run will show the errors from the first file (doctest stops if a
 file has errors).  Note that doctest test-run error output appears on stdout,
@@ -2922,7 +2916,7 @@ We should also check some typical error cases.
 Invalid file name:
 
     >>> rc, out, err = script_helper.assert_python_failure(
-    ...         '-m', 'doctest', 'nosuchfile', TERM='')
+    ...         '-m', 'doctest', 'nosuchfile')
     >>> rc, out
     (1, b'')
     >>> print(normalize(err))                    # doctest: +ELLIPSIS
@@ -2933,7 +2927,7 @@ Invalid file name:
 Invalid doctest option:
 
     >>> rc, out, err = script_helper.assert_python_failure(
-    ...         '-m', 'doctest', '-o', 'nosuchoption', TERM='')
+    ...         '-m', 'doctest', '-o', 'nosuchoption')
     >>> rc, out
     (2, b'')
     >>> print(normalize(err))                    # doctest: +ELLIPSIS