diff --git a/scripts/Testing/Testcases/config_tests.xml b/scripts/Testing/Testcases/config_tests.xml
index 750c6fc3439c..d0ddac2690d9 100644
--- a/scripts/Testing/Testcases/config_tests.xml
+++ b/scripts/Testing/Testcases/config_tests.xml
@@ -367,7 +367,10 @@ LII    CLM initial condition interpolation test
     <INFO_DBUG>1</INFO_DBUG>
     <BFBFLAG>TRUE</BFBFLAG>
     <BUILD_THREADED>TRUE</BUILD_THREADED>
-    <REST_OPTION>never</REST_OPTION>
+    <CONTINUE_RUN>FALSE</CONTINUE_RUN>
+    <REST_OPTION>none</REST_OPTION>
+    <HIST_OPTION>$STOP_OPTION</HIST_OPTION>
+    <HIST_N>$STOP_N</HIST_N>
     <CCSM_TCOST>1</CCSM_TCOST>
     <DOUT_S>FALSE</DOUT_S>
   </test>
diff --git a/utils/python/CIME/SystemTests/pet.py b/utils/python/CIME/SystemTests/pet.py
index 4810f72cb381..aae40508fcf5 100644
--- a/utils/python/CIME/SystemTests/pet.py
+++ b/utils/python/CIME/SystemTests/pet.py
@@ -6,63 +6,41 @@
 (2) do another initial run with nthrds=1 for all components (suffix: single_thread)
 """
 
-import shutil
 from CIME.XML.standard_module_setup import *
 from CIME.case_setup import case_setup
-from CIME.SystemTests.system_tests_common import SystemTestsCommon
+from CIME.SystemTests.system_tests_compare_two import SystemTestsCompareTwo
 
 logger = logging.getLogger(__name__)
 
-class PET(SystemTestsCommon):
+class PET(SystemTestsCompareTwo):
+
+    _COMPONENT_LIST = ('ATM','CPL','OCN','WAV','GLC','ICE','ROF','LND')
 
     def __init__(self, case):
         """
         initialize a test object
         """
-        SystemTestsCommon.__init__(self, case)
+        SystemTestsCompareTwo.__init__(self, case,
+                                       separate_builds = False,
+                                       run_two_suffix = 'single_thread',
+                                       run_one_description = 'default threading',
+                                       run_two_description = 'threads set to 1')
 
-    def build_phase(self, sharedlib_only=False, model_only=False):
+    def _case_one_setup(self):
         # first make sure that all components have threaded settings
-        for comp in ['ATM','CPL','OCN','WAV','GLC','ICE','ROF','LND']:
+        for comp in self._COMPONENT_LIST:
             if self._case.get_value("NTHRDS_%s"%comp) <= 1:
                 self._case.set_value("NTHRDS_%s"%comp, 2)
-        self._case.flush()
 
+        # TODO(wjs, 2016-08-16) Is this needed? I'm thinking it may be because
+        # we changed the number of threads, but I'm not sure
         case_setup(self._case, reset=True)
 
-        self.clean_build()
-        self.build_indv(sharedlib_only=sharedlib_only, model_only=model_only)
-
-    def _pet_first_phase(self):
-        #Do a run with default threading
-        self._case.set_value("CONTINUE_RUN",False)
-        self._case.set_value("REST_OPTION","none")
-        self._case.set_value("HIST_OPTION","$STOP_OPTION")
-        self._case.set_value("HIST_N","$STOP_N")
-        self._case.flush()
-
-        stop_n = self._case.get_value("STOP_N")
-        stop_option = self._case.get_value("STOP_OPTION")
-        logger.info("doing a %d %s initial test with default threading, no restarts written"
-                    % (stop_n, stop_option))
-
-        self.run_indv()
-
-    def _pet_second_phase(self):
+    def _case_two_setup(self):
         #Do a run with all threads set to 1
-        for comp in ['ATM','CPL','OCN','WAV','GLC','ICE','ROF','LND']:
+        for comp in self._COMPONENT_LIST:
             self._case.set_value("NTHRDS_%s"%comp, 1)
-        self._case.flush()
-        shutil.copy("env_mach_pes.xml", os.path.join("LockedFiles","env_mach_pes.xml"))
-
-        stop_n = self._case.get_value("STOP_N")
-        stop_option = self._case.get_value("STOP_OPTION")
-        logger.info("doing a %d %s initial test with threads set to 1, no restarts written"
-                    % (stop_n, stop_option))
 
-        self.run_indv(suffix="single_thread")
-        self._component_compare_test("base", "single_thread")
-
-    def run_phase(self):
-        self._pet_first_phase()
-        self._pet_second_phase()
+        # TODO(wjs, 2016-08-16) Is this needed? I'm thinking it may be because
+        # we changed the number of threads, but I'm not sure
+        case_setup(self._case, reset=True)