diff --git a/lib/matplotlib/axes/_subplots.py b/lib/matplotlib/axes/_subplots.py
index fd3754e7ea53..4c93ed996a16 100644
--- a/lib/matplotlib/axes/_subplots.py
+++ b/lib/matplotlib/axes/_subplots.py
@@ -173,7 +173,10 @@ def _make_twin_axes(self, *kl, **kwargs):
         """
         from matplotlib.projections import process_projection_requirements
         if 'sharex' in kwargs and 'sharey' in kwargs:
-            raise ValueError("Twinned Axes may share only one axis.")
+            # The following line is added in v2.2 to avoid breaking Seaborn,
+            # which currently uses this internal API.
+            if kwargs["sharex"] is not self and kwargs["sharey"] is not self:
+                raise ValueError("Twinned Axes may share only one axis.")
         kl = (self.get_subplotspec(),) + kl
         projection_class, kwargs, key = process_projection_requirements(
             self.figure, *kl, **kwargs)