diff --git a/INSTALL.rst b/INSTALL.rst
index cb49e4033dd0..d7d4ff594c8b 100644
--- a/INSTALL.rst
+++ b/INSTALL.rst
@@ -198,12 +198,13 @@ etc., you can install the following:
 FreeType and Qhull
 ------------------
 
-Matplotlib depends on `FreeType <https://www.freetype.org/>`_ (>= 2.3), a
-font rendering library, and on `Qhull <http://www.qhull.org/>`_ (>= 2015.2),
-a library for computing triangulations.  By default, Matplotlib downloads and
-builds its own copy of FreeType (this is necessary to run the test suite,
-because different versions of FreeType rasterize characters differently), and
-uses its own copy of Qhull.
+Matplotlib depends on `FreeType <https://www.freetype.org/>`_ (>=
+2.3), a font rendering library, and on `Qhull
+<http://www.qhull.org/>`_ (>= 2015.2), a library for computing
+triangulations.  By default (except on AIX) Matplotlib downloads and
+builds its own copy of FreeType (this is necessary to run the test
+suite, because different versions of FreeType rasterize characters
+differently), and uses its own copy of Qhull.
 
 To force Matplotlib to use a copy of FreeType or Qhull already installed in
 your system, create a :file:`setup.cfg` file with the following contents:
diff --git a/setupext.py b/setupext.py
index 3a6d6c1e412c..21bec048bdd4 100644
--- a/setupext.py
+++ b/setupext.py
@@ -137,8 +137,8 @@ def download_or_cache(url, sha):
     config.read(setup_cfg)
 options = {
     'backend': config.get('rc_options', 'backend', fallback=None),
-    'system_freetype': config.getboolean('libs', 'system_freetype',
-                                         fallback=False),
+    'system_freetype': config.getboolean(
+        'libs', 'system_freetype', fallback=sys.platform.startswith('aix')),
     'system_qhull': config.getboolean('libs', 'system_qhull',
                                       fallback=False),
 }