diff --git a/Doc/library/re.rst b/Doc/library/re.rst
index 2d5e1956ce3..df63f9bec28 100644
--- a/Doc/library/re.rst
+++ b/Doc/library/re.rst
@@ -332,7 +332,8 @@ the second character.  For example, ``\$`` matches the character ``'$'``.
 ``\d``
    When the :const:`UNICODE` flag is not specified, matches any decimal digit; this
    is equivalent to the set ``[0-9]``.  With :const:`UNICODE`, it will match
-   whatever is classified as a digit in the Unicode character properties database.
+   whatever is classified as a decimal digit in the Unicode character properties
+   database.
 
 ``\D``
    When the :const:`UNICODE` flag is not specified, matches any non-digit
diff --git a/Lib/test/test_re.py b/Lib/test/test_re.py
index 4f543d93dd9..c4cc8208ede 100644
--- a/Lib/test/test_re.py
+++ b/Lib/test/test_re.py
@@ -636,6 +636,27 @@ class ReTests(unittest.TestCase):
         self.assertEqual(iter.next().span(), (4, 4))
         self.assertRaises(StopIteration, iter.next)
 
+    def test_bug_6561(self):
+        # '\d' should match characters in Unicode category 'Nd'
+        # (Number, Decimal Digit), but not those in 'Nl' (Number,
+        # Letter) or 'No' (Number, Other).
+        decimal_digits = [
+            u'\u0037', # '\N{DIGIT SEVEN}', category 'Nd'
+            u'\u0e58', # '\N{THAI DIGIT SIX}', category 'Nd'
+            u'\uff10', # '\N{FULLWIDTH DIGIT ZERO}', category 'Nd'
+            ]
+        for x in decimal_digits:
+            self.assertEqual(re.match('^\d$', x, re.UNICODE).group(0), x)
+
+        not_decimal_digits = [
+            u'\u2165', # '\N{ROMAN NUMERAL SIX}', category 'Nl'
+            u'\u3039', # '\N{HANGZHOU NUMERAL TWENTY}', category 'Nl'
+            u'\u2082', # '\N{SUBSCRIPT TWO}', category 'No'
+            u'\u32b4', # '\N{CIRCLED NUMBER THIRTY NINE}', category 'No'
+            ]
+        for x in not_decimal_digits:
+            self.assertIsNone(re.match('^\d$', x, re.UNICODE))
+
     def test_empty_array(self):
         # SF buf 1647541
         import array
diff --git a/Misc/NEWS b/Misc/NEWS
index 25bbabb72cd..6731fb93e16 100644
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -1205,6 +1205,10 @@ C-API
 Extension Modules
 -----------------
 
+- Issue #6561: '\d' in a regex now matches only characters with
+  Unicode category 'Nd' (Number, Decimal Digit).  Previously it also
+  matched characters with category 'No'.
+
 - Issue #1523: Remove deprecated overflow wrapping for struct.pack
   with an integer format code ('bBhHiIlLqQ').  Packing an out-of-range
   integer now consistently raises struct.error.
diff --git a/Modules/_sre.c b/Modules/_sre.c
index 1aea53bf94e..0d9ee24eae7 100644
--- a/Modules/_sre.c
+++ b/Modules/_sre.c
@@ -172,7 +172,7 @@ static unsigned int sre_lower_locale(unsigned int ch)
 
 #if defined(HAVE_UNICODE)
 
-#define SRE_UNI_IS_DIGIT(ch) Py_UNICODE_ISDIGIT((Py_UNICODE)(ch))
+#define SRE_UNI_IS_DIGIT(ch) Py_UNICODE_ISDECIMAL((Py_UNICODE)(ch))
 #define SRE_UNI_IS_SPACE(ch) Py_UNICODE_ISSPACE((Py_UNICODE)(ch))
 #define SRE_UNI_IS_LINEBREAK(ch) Py_UNICODE_ISLINEBREAK((Py_UNICODE)(ch))
 #define SRE_UNI_IS_ALNUM(ch) Py_UNICODE_ISALNUM((Py_UNICODE)(ch))