diff --git a/builtin/log.c b/builtin/log.c
index 7d19578963..ab74760386 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -2415,6 +2415,7 @@ done:
 	strbuf_release(&rdiff_title);
 	strbuf_release(&sprefix);
 	free(to_free);
+	free(rev.message_id);
 	if (rev.ref_message_ids)
 		string_list_clear(rev.ref_message_ids, 0);
 	free(rev.ref_message_ids);
diff --git a/t/t9001-send-email.sh b/t/t9001-send-email.sh
index 2051103226..8d49eff91a 100755
--- a/t/t9001-send-email.sh
+++ b/t/t9001-send-email.sh
@@ -4,7 +4,7 @@ test_description='git send-email'
 GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME=main
 export GIT_TEST_DEFAULT_INITIAL_BRANCH_NAME
 
-# no longer TEST_PASSES_SANITIZE_LEAK=true - format-patch --thread leaks
+TEST_PASSES_SANITIZE_LEAK=true
 . ./test-lib.sh
 
 # May be altered later in the test