diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index ecf3aa34ede..e246c36de01 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -857,8 +857,13 @@ class PyMemDebugTests(unittest.TestCase):
 
     def check(self, code):
         with support.SuppressCrashReport():
-            out = assert_python_failure('-c', code,
-                                        PYTHONMALLOC=self.PYTHONMALLOC)
+            out = assert_python_failure(
+                '-c', code,
+                PYTHONMALLOC=self.PYTHONMALLOC,
+                # FreeBSD: instruct jemalloc to not fill freed() memory
+                # with junk byte 0x5a, see JEMALLOC(3)
+                MALLOC_CONF="junk:false",
+            )
         stderr = out.err
         return stderr.decode('ascii', 'replace')
 
diff --git a/Misc/NEWS.d/next/Tests/2022-01-06-15-45-34.bpo-46263.bJXek6.rst b/Misc/NEWS.d/next/Tests/2022-01-06-15-45-34.bpo-46263.bJXek6.rst
new file mode 100644
index 00000000000..0334af4e3cb
--- /dev/null
+++ b/Misc/NEWS.d/next/Tests/2022-01-06-15-45-34.bpo-46263.bJXek6.rst
@@ -0,0 +1,2 @@
+Fix test_capi on FreeBSD 14-dev: instruct jemalloc to not fill freed memory
+with junk byte.