diff --git a/platform/posix/SConscript b/platform/posix/SConscript
index 7c55cc245..a3a20130a 100644
--- a/platform/posix/SConscript
+++ b/platform/posix/SConscript
@@ -11,19 +11,31 @@ if env['INSTALL_MANPAGES']:
 
 ### Generate customized scripts ###
 
+# If any Python 3 package is built, prefer that one. If not,
+# and if any Python 2 package is built, prefer that one.
+# In all other cases, use the Python 3 location variables,
+# which should all be empty strings
+if env['python3_package'] in ['full', 'minimal']:
+    major = '3'
+elif env['python2_package'] in ['full', 'minimal']:
+    major = '2'
+else:
+    major = '3'
+
 # 'setup_cantera'
 if localenv['layout'] != 'debian' and env['OS'] != 'Windows':
-    v = sys.version_info
 
     def copy_var(target, source, env):
-        if env['python_prefix'] == 'USER':
+        if env['python{}_prefix'.format(major)] == 'USER':
             env['python_module_loc_sc'] = ''
         else:
-            env['python_module_loc_sc'] = env['python_module_loc']
+            env['python_module_loc_sc'] = env['python{}_module_loc'.format(major)]
+        env['python_cmd'] = env['python{}_cmd'.format(major)]
+        env['python_array_home'] = env['python{}_array_home'.format(major)]
 
     target = env.SubstFile('setup_cantera', 'setup_cantera.in')
     localenv.AddPreAction(target, copy_var)
-    localenv.Depends(target, env['install_python2_action'])
+    localenv.Depends(target, env['install_python{}_action'.format(major)])
     install('$inst_bindir', target)
 
 # Cantera.mak include file for Makefile projects
diff --git a/platform/posix/setup_cantera.in b/platform/posix/setup_cantera.in
index b40cc185c..81fd48324 100644
--- a/platform/posix/setup_cantera.in
+++ b/platform/posix/setup_cantera.in
@@ -35,9 +35,9 @@ fi
 
 if [ "@python_module_loc_sc@" != "" ]; then
     if [ -z $PYTHONPATH ]; then
-        PYTHONPATH=@python_module_loc@
+        PYTHONPATH=@python_module_loc_sc@
     else
-        PYTHONPATH=@python_module_loc@:$PYTHONPATH
+        PYTHONPATH=@python_module_loc_sc@:$PYTHONPATH
     fi
 fi
 
diff --git a/src/matlab/SConscript b/src/matlab/SConscript
index ff33ad7b1..cd455a233 100644
--- a/src/matlab/SConscript
+++ b/src/matlab/SConscript
@@ -79,16 +79,29 @@ env['matlab_extension'] = ctmethods
 
 # 'ctpath.m'
 globalenv = env
+
+# If any Python 3 package is built, prefer that one. If not,
+# and if any Python 2 package is built, prefer that one.
+# In all other cases, use the Python 3 location variables,
+# which should all be empty strings
+if env['python3_package'] in ['full', 'minimal']:
+    major = '3'
+elif env['python2_package'] in ['full', 'minimal']:
+    major = '2'
+else:
+    major = '3'
+
 def copy_var(target, source, env):
-    if env['python_prefix'] == 'USER':
+    if env['python{}_prefix'.format(major)] == 'USER':
         env['python_module_loc_sc'] = ''
     else:
-        env['python_module_loc_sc'] = globalenv['python_module_loc']
+        env['python_module_loc_sc'] = globalenv['python{}_module_loc'.format(major)]
+    env['python_cmd'] = env['python{}_cmd'.format(major)]
 
 target = localenv.SubstFile('#interfaces/matlab/ctpath.m',
                             '#interfaces/matlab/ctpath.m.in')
 localenv.AddPreAction(target, copy_var)
-localenv.Depends(target, env['install_python2_action'])
+localenv.Depends(target, env['install_python{}_action'.format(major)])
 install('$inst_matlab_dir', target)
 
 # 'Contents.m'