diff --git a/lib/matplotlib/offsetbox.py b/lib/matplotlib/offsetbox.py
@@ -369,15 +369,15 @@ def draw(self, renderer):
 
 
 class PackerBase(OffsetBox):
-    def __init__(self, pad=None, sep=None, width=None, height=None,
+    def __init__(self, pad=0., sep=0., width=None, height=None,
                  align="baseline", mode="fixed", children=None):
         """
         Parameters
         ----------
-        pad : float, optional
+        pad : float, default: 0.0
             The boundary padding in points.
 
-        sep : float, optional
+        sep : float, default: 0.0
             The spacing between items in points.
 
         width, height : float, optional
@@ -502,13 +502,13 @@ class PaddedBox(OffsetBox):
     """
 
     @_api.make_keyword_only("3.6", name="draw_frame")
-    def __init__(self, child, pad=None, draw_frame=False, patch_attrs=None):
+    def __init__(self, child, pad=0., draw_frame=False, patch_attrs=None):
         """
         Parameters
         ----------
         child : `~matplotlib.artist.Artist`
             The contained `.Artist`.
-        pad : float
+        pad : float, default: 0.0
             The padding in points. This will be scaled with the renderer dpi.
             In contrast, *width* and *height* are in *pixels* and thus not
             scaled.
@@ -1242,13 +1242,13 @@ def __init__(self, offsetbox, xy,
             The position *(x, y)* to place the text at. The coordinate system
             is determined by *boxcoords*.
 
-        xycoords : str or `.Artist` or `.Transform` or callable or \
-(float, float), default: 'data'
+        xycoords : single or two-tuple of str or `.Artist` or `.Transform` or \
+callable, default: 'data'
             The coordinate system that *xy* is given in. See the parameter
             *xycoords* in `.Annotation` for a detailed description.
 
-        boxcoords : str or `.Artist` or `.Transform` or callable or \
-(float, float), default: value of *xycoords*
+        boxcoords : single or two-tuple of str or `.Artist` or `.Transform` \
+or callable, default: value of *xycoords*
             The coordinate system that *xybox* is given in. See the parameter
             *textcoords* in `.Annotation` for a detailed description.
 

diff --git a/lib/matplotlib/tests/test_offsetbox.py b/lib/matplotlib/tests/test_offsetbox.py
@@ -13,7 +13,7 @@
 
 from matplotlib.offsetbox import (
     AnchoredOffsetbox, AnnotationBbox, AnchoredText, DrawingArea, OffsetBox,
-    OffsetImage, TextArea, _get_packed_offsets, HPacker, VPacker)
+    OffsetImage, PaddedBox, TextArea, _get_packed_offsets, HPacker, VPacker)
 
 
 @image_comparison(['offsetbox_clipping'], remove_text=True)
@@ -347,8 +347,9 @@ def test_packers(align):
     r1 = DrawingArea(x1, y1)
     r2 = DrawingArea(x2, y2)
 
-    hpacker = HPacker(children=[r1, r2], pad=0, sep=0, align=align)
-    vpacker = VPacker(children=[r1, r2], pad=0, sep=0, align=align)
+    hpacker = HPacker(children=[r1, r2], align=align)
+    vpacker = VPacker(children=[r1, r2], align=align)
+
     renderer = fig.canvas.get_renderer()
 
     # HPacker
@@ -378,3 +379,12 @@ def test_packers(align):
         x_height = (x2 - x1) / 2
     # x-offsets, y-offsets
     assert_allclose([(x_height, 0), (0, -y2)], offset_pairs)
+
+
+def test_paddedbox():
+    # smoke test paddedbox for correct default value
+    fig, ax = plt.subplots()
+    at = AnchoredText("foo",  'upper left')
+    pb = PaddedBox(at, patch_attrs={'facecolor': 'r'}, draw_frame=True)
+    ax.add_artist(pb)
+    fig.draw_without_rendering()