diff --git a/lib/matplotlib/backends/backend_pdf.py b/lib/matplotlib/backends/backend_pdf.py
index e8e8ece1310c..a3e30926a6f4 100644
--- a/lib/matplotlib/backends/backend_pdf.py
+++ b/lib/matplotlib/backends/backend_pdf.py
@@ -15,11 +15,13 @@
 import os
 import re
 import struct
+import tempfile
 import time
 import types
 import warnings
 import zlib
 
+from fontTools import subset
 import numpy as np
 from PIL import Image
 
@@ -36,7 +38,7 @@
 import matplotlib.type1font as type1font
 import matplotlib.dviread as dviread
 from matplotlib.ft2font import (FIXED_WIDTH, ITALIC, LOAD_NO_SCALE,
-                                LOAD_NO_HINTING, KERNING_UNFITTED)
+                                LOAD_NO_HINTING, KERNING_UNFITTED, FT2Font)
 from matplotlib.mathtext import MathTextParser
 from matplotlib.transforms import Affine2D, BboxBase
 from matplotlib.path import Path
@@ -1146,6 +1148,23 @@ def embedTTFType42(font, characters, descriptor):
             wObject = self.reserveObject('Type 0 widths')
             toUnicodeMapObject = self.reserveObject('ToUnicode map')
 
+            print(f"SUBSET {filename} characters: "
+                  f"{''.join(chr(c) for c in characters)}")
+            fontdata = self.getSubset(
+                filename,
+                ''.join(chr(c) for c in characters)
+            )
+            print(f'SUBSET {filename} {os.stat(filename).st_size}'
+                  f' ↦ {len(fontdata)}')
+
+            # reload the font object from the subset
+            # (all the necessary data could probably be obtained directly
+            # using fontLib.ttLib)
+            with tempfile.NamedTemporaryFile(suffix='.ttf') as tmp:
+                tmp.write(fontdata)
+                tmp.seek(0, 0)
+                font = FT2Font(tmp.name)
+
             cidFontDict = {
                 'Type': Name('Font'),
                 'Subtype': Name('CIDFontType2'),
@@ -1170,21 +1189,12 @@ def embedTTFType42(font, characters, descriptor):
 
             # Make fontfile stream
             descriptor['FontFile2'] = fontfileObject
-            length1Object = self.reserveObject('decoded length of a font')
             self.beginStream(
                 fontfileObject.id,
                 self.reserveObject('length of font stream'),
-                {'Length1': length1Object})
-            with open(filename, 'rb') as fontfile:
-                length1 = 0
-                while True:
-                    data = fontfile.read(4096)
-                    if not data:
-                        break
-                    length1 += len(data)
-                    self.currentstream.write(data)
+                {'Length1': len(fontdata)})
+            self.currentstream.write(fontdata)
             self.endStream()
-            self.writeObject(length1Object, length1)
 
             # Make the 'W' (Widths) array, CidToGidMap and ToUnicode CMap
             # at the same time
@@ -1307,6 +1317,28 @@ def embedTTFType42(font, characters, descriptor):
         elif fonttype == 42:
             return embedTTFType42(font, characters, descriptor)
 
+    @classmethod
+    def getSubset(self, fontfile, characters):
+        """
+        Subset a TTF font
+
+        Reads the named fontfile and restricts the font to the characters.
+        Returns a serialization of the subset font as bytes.
+        """
+
+        options = subset.Options(glyph_names=True, recommended_glyphs=True)
+        options.drop_tables += ['FFTM']
+        font = subset.load_font(fontfile, options)
+        try:
+            subsetter = subset.Subsetter(options=options)
+            subsetter.populate(text=characters)
+            subsetter.subset(font)
+            fh = BytesIO()
+            font.save(fh, reorderTables=False)
+            return fh.getvalue()
+        finally:
+            font.close()
+
     def alphaState(self, alpha):
         """Return name of an ExtGState that sets alpha to the given value."""
 
diff --git a/lib/matplotlib/testing/conftest.py b/lib/matplotlib/testing/conftest.py
index 391dd5d49d38..8b8e3a8a3e9a 100644
--- a/lib/matplotlib/testing/conftest.py
+++ b/lib/matplotlib/testing/conftest.py
@@ -17,6 +17,8 @@ def pytest_configure(config):
         ("markers", "baseline_images: Compare output against references."),
         ("markers", "pytz: Tests that require pytz to be installed."),
         ("filterwarnings", "error"),
+        ("filterwarnings",
+         "ignore:.*The py23 module has been deprecated:DeprecationWarning"),
     ]:
         config.addinivalue_line(key, value)
 
diff --git a/setup.py b/setup.py
index 7f08fa09d6eb..b6556174d0e6 100644
--- a/setup.py
+++ b/setup.py
@@ -279,6 +279,7 @@ def build_extensions(self):
     ],
     install_requires=[
         "cycler>=0.10",
+        "fonttools>=4.13.0,<5.0",
         "kiwisolver>=1.0.1",
         "numpy>=1.16",
         "pillow>=6.2.0",