diff --git a/Doc/library/curses.ascii.rst b/Doc/library/curses.ascii.rst
index f3661d9bc5b..db3c8274069 100644
--- a/Doc/library/curses.ascii.rst
+++ b/Doc/library/curses.ascii.rst
@@ -115,12 +115,12 @@ C library:
 
 .. function:: isblank(c)
 
-   Checks for an ASCII whitespace character.
+   Checks for an ASCII whitespace character; space or horizontal tab.
 
 
 .. function:: iscntrl(c)
 
-   Checks for an ASCII control character (in the range 0x00 to 0x1f).
+   Checks for an ASCII control character (in the range 0x00 to 0x1f or 0x7f).
 
 
 .. function:: isdigit(c)
diff --git a/Lib/curses/ascii.py b/Lib/curses/ascii.py
index 800fd8b4b71..6a466e00786 100644
--- a/Lib/curses/ascii.py
+++ b/Lib/curses/ascii.py
@@ -54,13 +54,13 @@ def _ctoi(c):
 def isalnum(c): return isalpha(c) or isdigit(c)
 def isalpha(c): return isupper(c) or islower(c)
 def isascii(c): return _ctoi(c) <= 127          # ?
-def isblank(c): return _ctoi(c) in (8,32)
-def iscntrl(c): return _ctoi(c) <= 31
+def isblank(c): return _ctoi(c) in (9, 32)
+def iscntrl(c): return _ctoi(c) <= 31 or _ctoi(c) == 127
 def isdigit(c): return _ctoi(c) >= 48 and _ctoi(c) <= 57
 def isgraph(c): return _ctoi(c) >= 33 and _ctoi(c) <= 126
 def islower(c): return _ctoi(c) >= 97 and _ctoi(c) <= 122
 def isprint(c): return _ctoi(c) >= 32 and _ctoi(c) <= 126
-def ispunct(c): return _ctoi(c) != 32 and not isalnum(c)
+def ispunct(c): return isgraph(c) and not isalnum(c)
 def isspace(c): return _ctoi(c) in (9, 10, 11, 12, 13, 32)
 def isupper(c): return _ctoi(c) >= 65 and _ctoi(c) <= 90
 def isxdigit(c): return isdigit(c) or \
diff --git a/Lib/test/test_curses.py b/Lib/test/test_curses.py
index 8411cdb0f25..897d738f57d 100644
--- a/Lib/test/test_curses.py
+++ b/Lib/test/test_curses.py
@@ -10,6 +10,7 @@
 #
 
 import os
+import string
 import sys
 import tempfile
 import unittest
@@ -399,6 +400,55 @@ class MiscTests(unittest.TestCase):
 
 class TestAscii(unittest.TestCase):
 
+    def test_controlnames(self):
+        for name in curses.ascii.controlnames:
+            self.assertTrue(hasattr(curses.ascii, name), name)
+
+    def test_ctypes(self):
+        def check(func, expected):
+            with self.subTest(ch=c, func=func):
+                self.assertEqual(func(i), expected)
+                self.assertEqual(func(c), expected)
+
+        for i in range(256):
+            c = chr(i)
+            b = bytes([i])
+            check(curses.ascii.isalnum, b.isalnum())
+            check(curses.ascii.isalpha, b.isalpha())
+            check(curses.ascii.isdigit, b.isdigit())
+            check(curses.ascii.islower, b.islower())
+            check(curses.ascii.isspace, b.isspace())
+            check(curses.ascii.isupper, b.isupper())
+
+            check(curses.ascii.isascii, i < 128)
+            check(curses.ascii.ismeta, i >= 128)
+            check(curses.ascii.isctrl, i < 32)
+            check(curses.ascii.iscntrl, i < 32 or i == 127)
+            check(curses.ascii.isblank, c in ' \t')
+            check(curses.ascii.isgraph, 32 < i <= 126)
+            check(curses.ascii.isprint, 32 <= i <= 126)
+            check(curses.ascii.ispunct, c in string.punctuation)
+            check(curses.ascii.isxdigit, c in string.hexdigits)
+
+    def test_ascii(self):
+        ascii = curses.ascii.ascii
+        self.assertEqual(ascii('\xc1'), 'A')
+        self.assertEqual(ascii('A'), 'A')
+        self.assertEqual(ascii(ord('\xc1')), ord('A'))
+
+    def test_ctrl(self):
+        ctrl = curses.ascii.ctrl
+        self.assertEqual(ctrl('J'), '\n')
+        self.assertEqual(ctrl('\n'), '\n')
+        self.assertEqual(ctrl('@'), '\0')
+        self.assertEqual(ctrl(ord('J')), ord('\n'))
+
+    def test_alt(self):
+        alt = curses.ascii.alt
+        self.assertEqual(alt('\n'), '\x8a')
+        self.assertEqual(alt('A'), '\xc1')
+        self.assertEqual(alt(ord('A')), 0xc1)
+
     def test_unctrl(self):
         unctrl = curses.ascii.unctrl
         self.assertEqual(unctrl('a'), 'a')
@@ -408,9 +458,13 @@ class TestAscii(unittest.TestCase):
         self.assertEqual(unctrl('\x7f'), '^?')
         self.assertEqual(unctrl('\n'), '^J')
         self.assertEqual(unctrl('\0'), '^@')
+        self.assertEqual(unctrl(ord('A')), 'A')
+        self.assertEqual(unctrl(ord('\n')), '^J')
         # Meta-bit characters
         self.assertEqual(unctrl('\x8a'), '!^J')
         self.assertEqual(unctrl('\xc1'), '!A')
+        self.assertEqual(unctrl(ord('\x8a')), '!^J')
+        self.assertEqual(unctrl(ord('\xc1')), '!A')
 
 
 if __name__ == '__main__':
diff --git a/Misc/NEWS b/Misc/NEWS
index 3c6d3aed716..49304ba38e3 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -13,6 +13,8 @@ Core and Builtins
 Library
 -------
 
+- Issue #27079: Fixed curses.ascii functions isblank(), iscntrl() and ispunct().
+
 - Issue #26754: Some functions (compile() etc) accepted a filename argument
   encoded as an iterable of integers. Now only strings and byte-like objects
   are accepted.