matplotlib
diff --git a/‎lib/matplotlib/tests/test_ticker.py
Copy file name to clipboardExpand all lines: lib/matplotlib/tests/test_ticker.py
+18Lines changed: 18 additions & 0 deletions b/‎lib/matplotlib/tests/test_ticker.py
Copy file name to clipboardExpand all lines: lib/matplotlib/tests/test_ticker.py
+18Lines changed: 18 additions & 0 deletions
diff --git a/‎lib/matplotlib/ticker.py
Copy file name to clipboardExpand all lines: lib/matplotlib/ticker.py
+8-2Lines changed: 8 additions & 2 deletions b/‎lib/matplotlib/ticker.py
Copy file name to clipboardExpand all lines: lib/matplotlib/ticker.py
+8-2Lines changed: 8 additions & 2 deletions
@@ -1449,6 +1449,24 @@ def test_latex(self, is_latex, usetex, expected):
             assert fmt.format_pct(50, 100) == expected
 
 
+def test_locale_comma():
+    currentLocale = locale.getlocale()
+    try:
+        locale.setlocale(locale.LC_ALL, 'de_DE.UTF-8')
+        ticks = mticker.ScalarFormatter(useMathText=True, useLocale=True)
+        fmt = '$\\mathdefault{%1.1f}$'
+        x = ticks._format_maybe_minus_and_locale(fmt, 0.5)
+        assert x == '$\\mathdefault{0{,}5}$'
+        # Do not change , in the format string
+        fmt = ',$\\mathdefault{,%1.1f},$'
+        x = ticks._format_maybe_minus_and_locale(fmt, 0.5)
+        assert x == ',$\\mathdefault{,0{,}5},$'
+    except locale.Error:
+        pytest.skip("Locale de_DE.UTF-8 is not supported on this machine")
+    finally:
+        locale.setlocale(locale.LC_ALL, currentLocale)
+
+
 def test_majformatter_type():
     fig, ax = plt.subplots()
     with pytest.raises(TypeError):
 
@@ -510,8 +510,14 @@ def _format_maybe_minus_and_locale(self, fmt, arg):
         """
         Format *arg* with *fmt*, applying Unicode minus and locale if desired.
         """
-        return self.fix_minus(locale.format_string(fmt, (arg,), True)
-                              if self._useLocale else fmt % arg)
+        return self.fix_minus(
+                # Escape commas introduced by format_string but not those present
+                # from the beginning in fmt.
+                ",".join(locale.format_string(part, (arg,), True)
+                         .replace(",", "{,}")
+                         for part in fmt.split(","))
+                if self._useLocale
+                else fmt % arg)
 
     def get_useMathText(self):
         """