@@ -1422,25 +1422,35 @@ def _update_ticks(self):
         if (self._tick_group_visible(self._major_tick_kw)
                 and not isinstance(self.get_major_locator(), NullLocator)):
             major_locs = self.get_majorticklocs()
-            major_labels = self.major.formatter.format_ticks(major_locs)
+            major_formatter = self.major.formatter
+            major_labels = major_formatter.format_ticks(major_locs)
+            major_is_custom = not self.isDefault_majfmt
             major_ticks = self.get_major_ticks(len(major_locs))
             for tick, loc, label in zip(major_ticks, major_locs, major_labels):
                 tick.update_position(loc)
                 tick.label1.set_text(label)
                 tick.label2.set_text(label)
+                # Custom formatters can produce labels with different
+                # ascenders, so let Text use a common line box for them.
+                tick.label1._is_ticklabel = major_is_custom
+                tick.label2._is_ticklabel = major_is_custom
         else:
             major_ticks = []
 
         # Check if minor ticks should be computed.
         if (self._tick_group_visible(self._minor_tick_kw)
                 and not isinstance(self.get_minor_locator(), NullLocator)):
             minor_locs = self.get_minorticklocs()
-            minor_labels = self.minor.formatter.format_ticks(minor_locs)
+            minor_formatter = self.minor.formatter
+            minor_labels = minor_formatter.format_ticks(minor_locs)
+            minor_is_custom = not self.isDefault_minfmt
             minor_ticks = self.get_minor_ticks(len(minor_locs))
             for tick, loc, label in zip(minor_ticks, minor_locs, minor_labels):
                 tick.update_position(loc)
                 tick.label1.set_text(label)
                 tick.label2.set_text(label)
+                tick.label1._is_ticklabel = minor_is_custom
+                tick.label2._is_ticklabel = minor_is_custom
         else:
             minor_ticks = []