diff --git a/t/t0612-reftable-jgit-compatibility.sh b/t/t0612-reftable-jgit-compatibility.sh
new file mode 100755
index 00000000000000..f25ea880a02a36
--- /dev/null
+++ b/t/t0612-reftable-jgit-compatibility.sh
@@ -0,0 +1,115 @@
+#!/bin/sh
+
+test_description='reftables are compatible with JGit'
+
+GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
+export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
+GIT_TEST_DEFAULT_REF_FORMAT=reftable
+export GIT_TEST_DEFAULT_REF_FORMAT
+
+# JGit does not support the 'link' DIRC extension.
+GIT_TEST_SPLIT_INDEX=0
+export GIT_TEST_SPLIT_INDEX
+
+. ./test-lib.sh
+
+if ! test_have_prereq JGIT
+then
+	skip_all='skipping reftable JGit tests'
+	test_done
+fi
+
+if ! test_have_prereq SHA1
+then
+	skip_all='skipping reftable JGit tests; JGit does not support SHA256 reftables'
+	test_done
+fi
+
+test_commit_jgit () {
+	touch "$1" &&
+	jgit add "$1" &&
+	jgit commit -m "$1"
+}
+
+test_same_refs () {
+	git show-ref --head >cgit.actual &&
+	jgit show-ref >jgit-tabs.actual &&
+	tr "\t" " " <jgit-tabs.actual >jgit.actual &&
+	test_cmp cgit.actual jgit.actual
+}
+
+test_same_reflog () {
+	git reflog "$*" >cgit.actual &&
+	jgit reflog "$*" >jgit-newline.actual &&
+	sed '/^$/d' <jgit-newline.actual >jgit.actual &&
+	test_cmp cgit.actual jgit.actual
+}
+
+test_expect_success 'CGit repository can be read by JGit' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+		test_commit A &&
+		test_same_refs &&
+		test_same_reflog HEAD
+	)
+'
+
+test_expect_success 'JGit repository can be read by CGit' '
+	test_when_finished "rm -rf repo" &&
+	# JGit does not provide a way to create a reftable-enabled repository.
+	git init repo &&
+	(
+		cd repo &&
+		touch file &&
+		jgit add file &&
+		jgit commit -m "initial commit" &&
+
+		test_same_refs &&
+		# Interestingly, JGit cannot read its own reflog here. CGit can
+		# though.
+		printf "%s HEAD@{0}: commit (initial): initial commit" "$(git rev-parse --short HEAD)" >expect &&
+		git reflog HEAD >actual &&
+		test_cmp expect actual
+	)
+'
+
+test_expect_success 'mixed writes from JGit and CGit' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		test_commit A &&
+		test_commit_jgit B &&
+		test_commit C &&
+		test_commit_jgit D &&
+
+		test_same_refs &&
+		test_same_reflog HEAD
+	)
+'
+
+test_expect_success 'JGit can read multi-level index' '
+	test_when_finished "rm -rf repo" &&
+	git init repo &&
+	(
+		cd repo &&
+
+		test_commit A &&
+		awk "
+		    BEGIN {
+			print \"start\";
+			for (i = 0; i < 10000; i++)
+			    printf \"create refs/heads/branch-%d HEAD\n\", i;
+			print \"commit\";
+		    }
+		" >input &&
+		git update-ref --stdin <input &&
+
+		test_same_refs
+	)
+'
+
+test_done