Try if sphinx is installed

setup.py

@@ -24,7 +24,20 @@
 import os
 import codecs
 from setuptools import setup
-from sphinx.setup_command import BuildDoc
+
+cmdclass = dict()
+command_options = dict()
+
+try:
+    from sphinx.setup_command import BuildDoc
+    cmdclass['build_sphinx'] = BuildDoc
+    # Override docs/conf.py settings
+    command_options['build_sphinx'] = {'project': ('dfetup.py', name),
+        'release':    ('dfetup.py', version),
+        'copyright':  ('dfetup.py', copyright),
+        'source_dir': ('dfetup.py', 'docs')}
+except:
+    pass
 
 
 # https://packaging.python.org/guides/single-sourcing-package-version/
@@ -59,12 +72,6 @@ setup(
     install_requires=[],
     package_data={'pymagglobal': ['dat/*']},
     include_package_data=True,
-    cmdclass={'build_sphinx': BuildDoc},
-    # Override docs/conf.py settings
-    command_options={
-        'build_sphinx': {
-            'project':    ('dfetup.py', name),
-            'release':    ('dfetup.py', version),
-            'copyright':  ('dfetup.py', copyright),
-            'source_dir': ('dfetup.py', 'docs')}},
+    cmdclass=cmdclass,
+    command_options=command_options,
 )