diff --git a/lib/mpl_toolkits/mplot3d/art3d.py b/lib/mpl_toolkits/mplot3d/art3d.py
@@ -545,7 +545,7 @@ def set_3d_properties(self, zs, zdir):
         #
         # Grab the current sizes and linewidths to preserve them.
         self._sizes3d = self._sizes
-        self._linewidths3d = self._linewidths
+        self._linewidths3d = np.array(self._linewidths)
         xs, ys, zs = self._offsets3d
 
         # Sort the points based on z coordinates
@@ -563,7 +563,7 @@ def set_sizes(self, sizes, dpi=72.0):
     def set_linewidth(self, lw):
         super().set_linewidth(lw)
         if not self._in_draw:
-            self._linewidth3d = lw
+            self._linewidths3d = np.array(self._linewidths)
 
     def get_depthshade(self):
         return self._depthshade

diff --git a/lib/mpl_toolkits/tests/baseline_images/test_mplot3d/scatter3d_linewidth.png b/lib/mpl_toolkits/tests/baseline_images/test_mplot3d/scatter3d_linewidth.png
diff --git a/lib/mpl_toolkits/tests/test_mplot3d.py b/lib/mpl_toolkits/tests/test_mplot3d.py
@@ -299,6 +299,30 @@ def test_scatter3d_color():
                color='b', marker='s')
 
 
+@mpl3d_image_comparison(['scatter3d_linewidth.png'])
+def test_scatter3d_linewidth():
+    fig = plt.figure()
+    ax = fig.add_subplot(projection='3d')
+
+    # Check that array-like linewidth can be set
+    ax.scatter(np.arange(10), np.arange(10), np.arange(10),
+               marker='o', linewidth=np.arange(10))
+
+
+@check_figures_equal(extensions=['png'])
+def test_scatter3d_linewidth_modification(fig_ref, fig_test):
+    # Changing Path3DCollection linewidths with array-like post-creation
+    # should work correctly.
+    ax_test = fig_test.add_subplot(projection='3d')
+    c = ax_test.scatter(np.arange(10), np.arange(10), np.arange(10),
+                        marker='o')
+    c.set_linewidths(np.arange(10))
+
+    ax_ref = fig_ref.add_subplot(projection='3d')
+    ax_ref.scatter(np.arange(10), np.arange(10), np.arange(10), marker='o',
+                   linewidths=np.arange(10))
+
+
 @check_figures_equal(extensions=['png'])
 def test_scatter3d_modification(fig_ref, fig_test):
     # Changing Path3DCollection properties post-creation should work correctly.