diff --git a/ci/lib.sh b/ci/lib.sh
index c6ccbf8c17..a89f480a78 100755
--- a/ci/lib.sh
+++ b/ci/lib.sh
@@ -382,6 +382,7 @@ linux-leaks|linux-reftable-leaks)
 	export NO_CVS_TESTS=LetsSaveSomeTime
 	export NO_SVN_TESTS=LetsSaveSomeTime
 	export NO_P4_TESTS=LetsSaveSomeTime
+	GIT_TEST_OPTS="$GIT_TEST_OPTS --immediate"
 	;;
 linux-asan-ubsan)
 	export SANITIZE=address,undefined
diff --git a/t/test-lib-github-workflow-markup.sh b/t/test-lib-github-workflow-markup.sh
index fa29a62aa3..3fa7859f0b 100644
--- a/t/test-lib-github-workflow-markup.sh
+++ b/t/test-lib-github-workflow-markup.sh
@@ -28,6 +28,7 @@ start_test_output () {
 	github_markup_output="${GIT_TEST_TEE_OUTPUT_FILE%.out}.markup"
 	>$github_markup_output
 	GIT_TEST_TEE_OFFSET=0
+	github_markup_script_name=${0##*/}
 }
 
 # No need to override start_test_case_output
@@ -53,4 +54,13 @@ finalize_test_case_output () {
 	echo >>$github_markup_output "::endgroup::"
 }
 
+finalize_test_leak_output () {
+	echo >>$github_markup_output \
+		"::error::memory leak logged in $this_test ($github_markup_script_name)"
+
+	echo >>$github_markup_output "::group::leak: $this_test.$test_count"
+	cat "$TEST_RESULTS_SAN_FILE".* >>$github_markup_output
+	echo >>$github_markup_output "::endgroup::"
+}
+
 # No need to override finalize_test_output
diff --git a/t/test-lib.sh b/t/test-lib.sh
index 1f0505e412..e74a12f1dd 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -199,6 +199,7 @@ mark_option_requires_arg () {
 start_test_output () { :; }
 start_test_case_output () { :; }
 finalize_test_case_output () { :; }
+finalize_test_leak_output () { :; }
 finalize_test_output () { :; }
 
 parse_option () {
@@ -822,6 +823,9 @@ test_failure_ () {
 	say_color error "not ok $test_count - ${pfx:+$pfx }$1"
 	shift
 	printf '%s\n' "$*" | sed -e 's/^/#	/'
+	# Write the annotation before either --immediate exit path below,
+	# both of which call exit and would otherwise skip it.
+	finalize_test_case_output failure "$failure_label" "$@"
 	if test -n "$immediate"
 	then
 		say_color error "1..$test_count"
@@ -835,7 +839,6 @@ test_failure_ () {
 		check_test_results_san_file_ "$test_failure"
 		_error_exit
 	fi
-	finalize_test_case_output failure "$failure_label" "$@"
 }
 
 test_known_broken_ok_ () {
@@ -1218,6 +1221,7 @@ check_test_results_san_file_ () {
 		return
 	fi &&
 	say_color >&4 error "$(cat "$TEST_RESULTS_SAN_FILE".*)" &&
+	finalize_test_leak_output &&
 
 	if test "$test_failure" = 0
 	then