diff --git a/bin/tests/system/.gitignore b/bin/tests/system/.gitignore
index f946793ae7..6c34bfcd1a 100644
--- a/bin/tests/system/.gitignore
+++ b/bin/tests/system/.gitignore
@@ -24,10 +24,9 @@ parallel.mk
 /stop.sh
 /ifconfig.sh
 
-# Ignore file names with underscore in their name except python or shell files.
+# Ignore file names with a hyphen in their name except C files.
 # This is done to ignore the temporary directories and symlinks created by the
 # pytest runner, which contain underscore in their file names.
-/*_*
-!/*_*.py
-!/*_*.sh
-!/_common
+/*-*
+!/*-*.c
+!/custom-test-driver
diff --git a/bin/tests/system/Makefile.am b/bin/tests/system/Makefile.am
index d4526d2dd8..57b019bdc5 100644
--- a/bin/tests/system/Makefile.am
+++ b/bin/tests/system/Makefile.am
@@ -88,13 +88,13 @@ tkey_keydelete_LDADD =		\
 TESTS =				\
 	rpz			\
 	rpzrecurse		\
-	serve-stale		\
+	serve_stale		\
 	timeouts		\
 	upforwd			\
 	acl			\
 	additional		\
 	addzone			\
-	allow-query		\
+	allow_query		\
 	auth			\
 	autosign		\
 	builtin			\
@@ -117,7 +117,7 @@ TESTS =				\
 	dlzexternal		\
 	dns64			\
 	dnssec			\
-	dnssec-malformed-dnskey	\
+	dnssec_malformed_dnskey	\
 	dnstap			\
 	doth			\
 	dsdigest		\
@@ -128,14 +128,14 @@ TESTS =				\
 	ednscompliance		\
 	emptyzones		\
 	enginepkcs11		\
-	filter-aaaa		\
+	filter_aaaa		\
 	fetchlimit		\
 	formerr			\
 	forward			\
 	geoip2			\
 	glue			\
 	idna			\
-	include-multiplecfg	\
+	include_multiplecfg	\
 	inline			\
 	integrity		\
 	ixfr			\
@@ -189,7 +189,7 @@ TESTS =				\
 	tcp			\
 	tkey			\
 	tools			\
-	transport-acl		\
+	transport_acl		\
 	tsig			\
 	tsiggss			\
 	ttl			\
@@ -231,4 +231,4 @@ LOG_COMPILER = $(srcdir)/run.sh
 test-local: check
 
 clean-local::
-	-find -L . -mindepth 1 -maxdepth 1 -type d -name "*_*" -and -not -name "_common" -exec rm -rf {} \;
+	-find -L . -mindepth 1 -maxdepth 1 -type d -name "*-*" -exec rm -rf {} \;
diff --git a/bin/tests/system/conftest.py b/bin/tests/system/conftest.py
index 8fc9dd8a11..2f84bb108b 100644
--- a/bin/tests/system/conftest.py
+++ b/bin/tests/system/conftest.py
@@ -53,7 +53,7 @@ PRIORITY_TESTS = [
 PRIORITY_TESTS_RE = Re("|".join(PRIORITY_TESTS))
 SYSTEM_TEST_DIR_GIT_PATH = "bin/tests/system"
 SYSTEM_TEST_NAME_RE = Re(f"{SYSTEM_TEST_DIR_GIT_PATH}" + r"/([^/]+)")
-SYMLINK_REPLACEMENT_RE = Re(r"/tests(_.*)\.py")
+SYMLINK_REPLACEMENT_RE = Re(r"/tests_(.*)\.py")
 
 # ---------------------- Module initialization ---------------------------
 
@@ -132,14 +132,14 @@ def pytest_ignore_collect(collection_path):
     # ignore these during test collection phase. Otherwise, test artifacts
     # from previous runs could mess with the runner. Also ignore the
     # convenience symlinks to those test directories. In both of those
-    # cases, the system test name (directory) contains an underscore, which
+    # cases, the system test name (directory) contains a hyphen, which
     # is otherwise and invalid character for a system test name.
     match = SYSTEM_TEST_NAME_RE.search(str(collection_path))
     if match is None:
         isctest.log.warning("unexpected test path: %s (ignored)", collection_path)
         return True
     system_test_name = match.groups()[0]
-    return "_" in system_test_name
+    return "-" in system_test_name
 
 
 def pytest_collection_modifyitems(items):
@@ -449,13 +449,13 @@ def system_test_dir(request, env, system_test_name, expected_artifacts):
         f"{env['TOP_BUILDDIR']}/{SYSTEM_TEST_DIR_GIT_PATH}"
     ).resolve()
     testdir = Path(
-        tempfile.mkdtemp(prefix=f"{system_test_name}_tmp_", dir=system_test_root)
+        tempfile.mkdtemp(prefix=f"{system_test_name}-tmp-", dir=system_test_root)
     )
     shutil.rmtree(testdir)
     shutil.copytree(system_test_root / system_test_name, testdir)
 
     # Create a convenience symlink with a stable and predictable name
-    module_name = SYMLINK_REPLACEMENT_RE.sub(r"\1", str(request.node.path))
+    module_name = SYMLINK_REPLACEMENT_RE.sub(r"-\1", str(request.node.path))
     symlink_dst = system_test_root / module_name
     symlink_dst.unlink(missing_ok=True)
     symlink_dst.symlink_to(os.path.relpath(testdir, start=system_test_root))
diff --git a/dangerfile.py b/dangerfile.py
index b6851be7a5..c716934f09 100644
--- a/dangerfile.py
+++ b/dangerfile.py
@@ -494,10 +494,10 @@ for testname in testnames:
         or testname == "isctest"
     ):
         continue
-    if "_" in testname:
+    if "-" in testname:
         fail(
-            f"System test directory `{testname}` may not contain an underscore, "
-            "use hyphen instead."
+            f"System test directory `{testname}` may not contain a hyphen, "
+            "use underscore instead."
         )
     if not glob.glob(f"{dirpath}/**/tests_*.py", recursive=True):
         fail(