diff --git a/connect.c b/connect.c
index a0091acb1f..bdf2ca08ac 100644
--- a/connect.c
+++ b/connect.c
@@ -553,6 +553,11 @@ static struct child_process *git_proxy_connect(int fd[2], char *host)
 
 	get_host_and_port(&host, &port);
 
+	if (looks_like_command_line_option(host))
+		die("strange hostname '%s' blocked", host);
+	if (looks_like_command_line_option(port))
+		die("strange port '%s' blocked", port);
+
 	proxy = xmalloc(sizeof(*proxy));
 	child_process_init(proxy);
 	argv_array_push(&proxy->args, git_proxy_command);
diff --git a/t/t5532-fetch-proxy.sh b/t/t5532-fetch-proxy.sh
index 5531bd1af4..d3b2651b61 100755
--- a/t/t5532-fetch-proxy.sh
+++ b/t/t5532-fetch-proxy.sh
@@ -40,4 +40,9 @@ test_expect_success 'fetch through proxy works' '
 	test_cmp expect actual
 '
 
+test_expect_success 'funny hostnames are rejected before running proxy' '
+	test_must_fail git fetch git://-remote/repo.git 2>stderr &&
+	! grep "proxying for" stderr
+'
+
 test_done