diff --git a/serve.c b/serve.c
index 2b07d922b3dde1..5a6434446725a7 100644
--- a/serve.c
+++ b/serve.c
@@ -46,6 +46,9 @@ static int promisor_remote_advertise(struct repository *r,
 static void promisor_remote_receive(struct repository *r,
 				    const char *remotes)
 {
+	if (!remotes)
+		die("promisor-remote capability requires an argument");
+
 	mark_promisor_remotes_as_accepted(r, remotes);
 }
 
diff --git a/t/t5701-git-serve.sh b/t/t5701-git-serve.sh
index 9a575aa098afd3..d888cc5c3c5c1b 100755
--- a/t/t5701-git-serve.sh
+++ b/t/t5701-git-serve.sh
@@ -71,6 +71,17 @@ test_expect_success 'request invalid capability' '
 	test_grep "unknown capability" err
 '
 
+test_expect_success 'promisor-remote capability requires an argument' '
+	test-tool pkt-line pack >in <<-EOF &&
+	command=ls-refs
+	object-format=$(test_oid algo)
+	promisor-remote
+	0000
+	EOF
+	test_must_fail test-tool serve-v2 --stateless-rpc 2>err <in &&
+	test_grep "promisor-remote capability requires an argument" err
+'
+
 test_expect_success 'request with no command' '
 	test-tool pkt-line pack >in <<-EOF &&
 	agent=git/test