diff --git a/tests/conftest.py b/tests/conftest.py
index edfcedba3..b755d3984 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -117,16 +117,21 @@ def run_in_threads():
 
     A barrier releases every thread together, so concurrency tests do not
     need sleeps. The timeouts turn a deadlock into a failure rather than a
-    hung test run.
+    hung test run, and anything a worker raises is re-raised here rather
+    than being printed while the test carries on with a None result.
     """
 
     def _run(func, count=4, timeout=60):
         barrier = threading.Barrier(count, timeout=timeout)
         results = [None] * count
+        errors = []
 
         def worker(index):
-            barrier.wait()
-            results[index] = func(index)
+            try:
+                barrier.wait()
+                results[index] = func(index)
+            except BaseException as error:  # re-raised in the calling thread
+                errors.append(error)
 
         threads = [threading.Thread(target=worker, args=(i,)) for i in range(count)]
         for thread in threads:
@@ -134,6 +139,11 @@ def worker(index):
         for thread in threads:
             thread.join(timeout)
             assert not thread.is_alive(), "thread never finished; possible deadlock"
+        if errors:
+            # The first failure is re-raised as-is rather than aggregated:
+            # ExceptionGroup is 3.11+ while the package supports 3.10, and it
+            # rejects BaseException members such as pytest's own skip/fail.
+            raise errors[0]
         return results
 
     return _run