diff --git a/validate/launcher/apps/gstcheck.py b/validate/launcher/apps/gstcheck.py
index 7cd5a9445e..8b29fb8cf3 100644
--- a/validate/launcher/apps/gstcheck.py
+++ b/validate/launcher/apps/gstcheck.py
@@ -372,6 +372,7 @@ class GstCheckTestsManager(MesonTestsManager):
             to_inspect.append(test)
 
         if to_inspect:
+            assert self.options.num_jobs >= 0
             executor = conc.ThreadPoolExecutor(
                 max_workers=self.options.num_jobs)
             tmp = []
diff --git a/validate/launcher/baseclasses.py b/validate/launcher/baseclasses.py
index 67c48425a7..00832bc89a 100644
--- a/validate/launcher/baseclasses.py
+++ b/validate/launcher/baseclasses.py
@@ -2091,7 +2091,8 @@ class _TestsLauncher(Loggable):
             else:
                 alone_tests.append(test)
 
-        max_num_jobs = min(self.options.num_jobs, len(tests))
+        # use max to defend against the case where all tests are alone_tests
+        max_num_jobs = max(min(self.options.num_jobs, len(tests)), 1)
         jobs_running = 0
 
         if self.options.forever and len(tests) < self.options.num_jobs and len(tests):
diff --git a/validate/launcher/main.py b/validate/launcher/main.py
index 9214b80c89..745a7740d1 100644
--- a/validate/launcher/main.py
+++ b/validate/launcher/main.py
@@ -181,6 +181,13 @@ class PrintUsage(argparse.Action):
         parser.exit()
 
 
+def _positive_integer_type(value):
+    cast = int(value)
+    if cast <= 0:
+        raise argparse.ArgumentTypeError(f'`{value}\' is not a positive integer')
+    return cast
+
+
 class LauncherConfig(Loggable):
 
     def __init__(self):
@@ -210,7 +217,7 @@ class LauncherConfig(Loggable):
         self.logsdir = None
         self.privatedir = None
         self.redirect_logs = False
-        self.num_jobs = int(multiprocessing.cpu_count() / 2)
+        self.num_jobs = max(multiprocessing.cpu_count(), 1)
         self.dest = None
         self._using_default_paths = False
         # paths passed with --media-path, and not defined by a testsuite
@@ -543,8 +550,8 @@ class LauncherConfig(Loggable):
                                help="Redirect logs to stdout.")
         dir_group.add_argument("-j", "--jobs", dest="num_jobs",
                                help="Number of tests to execute simultaneously"
-                               " (Defaults to number of cores of the processor)",
-                               type=int)
+                               " (Defaults to the number of cores of the processor)",
+                               type=_positive_integer_type)
         dir_group.add_argument("--ignore-numfailures", dest="ignore_numfailures",
                                help="Ignore the number of failed test in exit code",
                                default=False, action='store_true')