diff --git a/ssh/tailssh/incubator.go b/ssh/tailssh/incubator.go
index ea54cbbf7..873559e76 100644
--- a/ssh/tailssh/incubator.go
+++ b/ssh/tailssh/incubator.go
@@ -206,7 +206,7 @@ func beIncubator(args []string) error {
 		// If we are trying to launch a login shell, just exec into login
 		// instead. We can only do this if a TTY was requested, otherwise login
 		// exits immediately, which breaks things likes mosh and VSCode.
-		return unix.Exec(ia.loginCmdPath, []string{ia.loginCmdPath, "-f", ia.localUser, "-h", ia.remoteIP, "-p"}, os.Environ())
+		return unix.Exec(ia.loginCmdPath, ia.loginArgs(), os.Environ())
 	}
 
 	// Inform the system that we are about to log someone in.
diff --git a/ssh/tailssh/incubator_darwin.go b/ssh/tailssh/incubator_darwin.go
new file mode 100644
index 000000000..d143883e6
--- /dev/null
+++ b/ssh/tailssh/incubator_darwin.go
@@ -0,0 +1,9 @@
+// Copyright (c) 2022 Tailscale Inc & AUTHORS All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package tailssh
+
+func (ia *incubatorArgs) loginArgs() []string {
+	return []string{ia.loginCmdPath, "-fp", "-h", ia.remoteIP, ia.localUser}
+}
diff --git a/ssh/tailssh/incubator_linux.go b/ssh/tailssh/incubator_linux.go
index 2c531c475..67ed2ca19 100644
--- a/ssh/tailssh/incubator_linux.go
+++ b/ssh/tailssh/incubator_linux.go
@@ -173,3 +173,7 @@ func maybeStartLoginSessionLinux(logf logger.Logf, ia incubatorArgs) (func() err
 	}
 	return nil, nil
 }
+
+func (ia *incubatorArgs) loginArgs() []string {
+	return []string{ia.loginCmdPath, "-f", ia.localUser, "-h", ia.remoteIP, "-p"}
+}