diff --git a/CIME/SystemTests/system_tests_common.py b/CIME/SystemTests/system_tests_common.py
index 3c1f3e99830..7295ea67ca1 100644
--- a/CIME/SystemTests/system_tests_common.py
+++ b/CIME/SystemTests/system_tests_common.py
@@ -38,7 +38,7 @@
 )
 import CIME.build as build
 
-import glob, gzip, time, traceback, os
+import glob, gzip, time, traceback, os, math
 from contextlib import ExitStack
 
 logger = logging.getLogger(__name__)
@@ -173,8 +173,8 @@ def _set_restart_interval(self):
         else:
             expect(False, f"stop_option {stop_option} not available for this test")
 
-        stop_n = int(stop_n * factor // coupling_secs)
-        rest_n = int((stop_n // 2 + 1) * coupling_secs / factor)
+        stop_n = stop_n * factor // coupling_secs
+        rest_n = math.ceil((stop_n // 2 + 1) * coupling_secs / factor)
 
         expect(stop_n > 0, "Bad STOP_N: {:d}".format(stop_n))