diff --git a/docs/source/devguide/workflow.rst b/docs/source/devguide/workflow.rst
index d33a282c7a..523fba32b2 100644
--- a/docs/source/devguide/workflow.rst
+++ b/docs/source/devguide/workflow.rst
@@ -158,4 +158,4 @@ from your private repository into a public fork.
 .. _mit-crpg/openmc: https://github.com/mit-crpg/openmc
 .. _paid plan: https://github.com/plans
 .. _Bitbucket: https://bitbucket.org
-.. _ctest: http://www.cmake.org/cmake/help/v2.8.8/ctest.html
+.. _ctest: http://www.cmake.org/cmake/help/v2.8.12/ctest.html
diff --git a/docs/source/usersguide/install.rst b/docs/source/usersguide/install.rst
index ee196552df..45e7671f52 100644
--- a/docs/source/usersguide/install.rst
+++ b/docs/source/usersguide/install.rst
@@ -490,4 +490,4 @@ schemas.xml file in your own OpenMC source directory.
 .. _GNU Emacs: http://www.gnu.org/software/emacs/
 .. _validation: http://en.wikipedia.org/wiki/XML_validation
 .. _RELAX NG: http://relaxng.org/
-.. _ctest: http://www.cmake.org/cmake/help/v2.8.8/ctest.html
+.. _ctest: http://www.cmake.org/cmake/help/v2.8.12/ctest.html
diff --git a/tests/readme.rst b/tests/readme.rst
index 3a340582b7..7c4d29e438 100644
--- a/tests/readme.rst
+++ b/tests/readme.rst
@@ -41,4 +41,4 @@ can run:
 
     python run_tests.py -p
 
-.. _ctest: http://www.cmake.org/cmake/help/v2.8.8/ctest.html
+.. _ctest: http://www.cmake.org/cmake/help/v2.8.12/ctest.html
diff --git a/tests/run_tests.py b/tests/run_tests.py
index 320fd71521..1e9f28238a 100755
--- a/tests/run_tests.py
+++ b/tests/run_tests.py
@@ -92,7 +92,7 @@ class Test(object):
         make_list = ['make','-s']
 
         # Check for parallel
-        if opts.n_procs != None:
+        if opts.n_procs is not None:
             make_list.append('-j')
             make_list.append(opts.n_procs)
 
@@ -110,12 +110,12 @@ class Test(object):
         ctest_list = ['ctest']
 
         # Check for parallel
-        if opts.n_procs != None:
+        if opts.n_procs is not None:
             ctest_list.append('-j')
             ctest_list.append(opts.n_procs)
 
         # Check for subset of tests
-        if opts.regex_tests != None:
+        if opts.regex_tests is not None:
             ctest_list.append('-R')
             ctest_list.append(opts.regex_tests)
 
@@ -179,14 +179,14 @@ if opts.print_build_configs:
     exit()
 
 # Delete items of dictionary that don't match regular expression
-if opts.build_config != None:
-    for key in iter(tests):
+if opts.build_config is not None:
+    for key in tests:
         if not re.search(opts.build_config, key):
             del tests[key]
 
 # Begin testing
-call(['rm','-rf','build'])
-for test in iter(tests):
+shutil.rmtree('build', ignore_errors=True)
+for test in tests:
     print('-'*(len(test) + 6))
     print(test + ' tests')
     print('-'*(len(test) + 6))
@@ -212,7 +212,7 @@ for test in iter(tests):
                     'LastTest_{0}.log'.format(test))
 
     # Clean up build
-    call(['rm','-rf','build'])
+    shutil.rmtree('build', ignore_errors=True)
 
 # Print out summary of results
 print('\n' + '='*54)