diff --git a/lib/matplotlib/colorbar.py b/lib/matplotlib/colorbar.py
index d418a216b016..6708e961bd50 100644
--- a/lib/matplotlib/colorbar.py
+++ b/lib/matplotlib/colorbar.py
@@ -598,7 +598,7 @@ def _central_N(self):
         nb = len(self._boundaries)
         if self.extend == 'both':
             nb -= 2
-        elif self._extend_lower():
+        elif self.extend in ('min', 'max'):
             nb -= 1
         return nb