diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
index 63b16c311810..a420599ceb40 100644
--- a/lib/matplotlib/axes/_axes.py
+++ b/lib/matplotlib/axes/_axes.py
@@ -50,16 +50,14 @@ def _make_inset_locator(bounds, trans, parent):
     location for the axes in the transform given by *trans* on the
     *parent*.
     """
-    _bounds = mtransforms.Bbox.from_bounds(*bounds)
-    _trans = trans
-    _parent = parent
+    bbox = mtransforms.Bbox.from_bounds(*bounds)
 
     def inset_locator(ax, renderer):
-        bbox = _bounds
-        bb = mtransforms.TransformedBbox(bbox, _trans)
-        tr = _parent.figure.transFigure.inverted()
-        bb = mtransforms.TransformedBbox(bb, tr)
-        return bb
+        # Subtracting transFigure will typically rely on inverted(), freezing
+        # the transform; thus, this needs to be delayed until draw time as
+        # transFigure may otherwise change after this is evaluated.
+        return mtransforms.TransformedBbox(
+            bbox, trans - parent.figure.transFigure)
 
     return inset_locator
 
diff --git a/lib/matplotlib/axes/_secondary_axes.py b/lib/matplotlib/axes/_secondary_axes.py
index 39b840833345..eb8d0ede9039 100644
--- a/lib/matplotlib/axes/_secondary_axes.py
+++ b/lib/matplotlib/axes/_secondary_axes.py
@@ -4,36 +4,10 @@
 import matplotlib.docstring as docstring
 import matplotlib.ticker as mticker
 import matplotlib.transforms as mtransforms
+from matplotlib.axes import _axes
 from matplotlib.axes._base import _AxesBase
 
 
-def _make_secondary_locator(rect, parent):
-    """
-    Helper function to locate the secondary axes.
-
-    A locator gets used in `Axes.set_aspect` to override the default
-    locations...  It is a function that takes an axes object and
-    a renderer and tells `set_aspect` where it is to be placed.
-
-    This locator make the transform be in axes-relative co-coordinates
-    because that is how we specify the "location" of the secondary axes.
-
-    Here *rect* is a rectangle [l, b, w, h] that specifies the
-    location for the axes in the transform given by *trans* on the
-    *parent*.
-    """
-    _rect = mtransforms.Bbox.from_bounds(*rect)
-    def secondary_locator(ax, renderer):
-        # delay evaluating transform until draw time because the
-        # parent transform may have changed (i.e. if window reesized)
-        bb = mtransforms.TransformedBbox(_rect, parent.transAxes)
-        tr = parent.figure.transFigure.inverted()
-        bb = mtransforms.TransformedBbox(bb, tr)
-        return bb
-
-    return secondary_locator
-
-
 class SecondaryAxis(_AxesBase):
     """
     General class to hold a Secondary_X/Yaxis.
@@ -137,11 +111,14 @@ def set_location(self, location):
         self._loc = location
 
         if self._orientation == 'x':
+            # An x-secondary axes is like an inset axes from x = 0 to x = 1 and
+            # from y = pos to y = pos + eps, in the parent's transAxes coords.
             bounds = [0, self._pos, 1., 1e-10]
         else:
             bounds = [self._pos, 0, 1e-10, 1]
 
-        secondary_locator = _make_secondary_locator(bounds, self._parent)
+        secondary_locator = _axes._make_inset_locator(
+            bounds, self._parent.transAxes, self._parent)
 
         # this locator lets the axes move in the parent axes coordinates.
         # so it never needs to know where the parent is explicitly in