diff --git a/lib/matplotlib/_layoutgrid.py b/lib/matplotlib/_layoutgrid.py
index 80a0ee2c86fb..8b7b140f600b 100644
--- a/lib/matplotlib/_layoutgrid.py
+++ b/lib/matplotlib/_layoutgrid.py
@@ -169,7 +169,8 @@ def hard_constraints(self):
                 self.solver.addConstraint(c | 'required')
 
     def add_child(self, child, i=0, j=0):
-        self.children[i, j] = child
+        # np.ix_ returns the cross product of i and j indices
+        self.children[np.ix_(np.atleast_1d(i), np.atleast_1d(j))] = child
 
     def parent_constraints(self):
         # constraints that are due to the parent...
diff --git a/lib/matplotlib/tests/test_constrainedlayout.py b/lib/matplotlib/tests/test_constrainedlayout.py
index a8222a73d5ee..a717eace8348 100644
--- a/lib/matplotlib/tests/test_constrainedlayout.py
+++ b/lib/matplotlib/tests/test_constrainedlayout.py
@@ -560,3 +560,10 @@ def test_suplabels():
     pos = ax.get_tightbbox(fig.canvas.get_renderer())
     assert pos.y0 > pos0.y0 + 10.0
     assert pos.x0 > pos0.x0 + 10.0
+
+
+def test_gridspec_addressing():
+    fig = plt.figure()
+    gs = fig.add_gridspec(3, 3)
+    sp = fig.add_subplot(gs[0:, 1:])
+    fig.draw_without_rendering()
diff --git a/lib/matplotlib/tests/test_figure.py b/lib/matplotlib/tests/test_figure.py
index bc2256ce3c54..cb8f63893aea 100644
--- a/lib/matplotlib/tests/test_figure.py
+++ b/lib/matplotlib/tests/test_figure.py
@@ -1073,6 +1073,7 @@ def test_subfigure_spanning():
         fig.add_subfigure(gs[0, 0]),
         fig.add_subfigure(gs[0:2, 1]),
         fig.add_subfigure(gs[2, 1:3]),
+        fig.add_subfigure(gs[0:, 1:])
     ]
 
     w = 640
@@ -1086,6 +1087,12 @@ def test_subfigure_spanning():
     np.testing.assert_allclose(sub_figs[2].bbox.min, [w / 3, 0])
     np.testing.assert_allclose(sub_figs[2].bbox.max, [w, h / 3])
 
+    # check here that slicing actually works.  Last sub_fig
+    # with open slices failed, but only on draw...
+    for i in range(4):
+        sub_figs[i].add_subplot()
+    fig.draw_without_rendering()
+
 
 @mpl.style.context('mpl20')
 def test_subfigure_ticks():