diff --git a/tailscale.go b/tailscale.go
index c78fb3f..e7b8f20 100644
--- a/tailscale.go
+++ b/tailscale.go
@@ -201,6 +201,9 @@ func TsnetListenerClose(ld C.int) C.int {
 	defer listeners.mu.Unlock()
 
 	l := listeners.m[ld]
+	if l == nil {
+		return C.EBADF
+	}
 	err := l.ln.Close()
 	delete(listeners.m, ld)
 
diff --git a/tailscale.h b/tailscale.h
index 73618cc..daa6f20 100644
--- a/tailscale.h
+++ b/tailscale.h
@@ -103,7 +103,10 @@ extern int tailscale_listen(tailscale sd, const char* network, const char* addr,
 
 // tailscale_listener_close closes the listener.
 //
-// Returns zero on success or -1 on error, call tailscale_errmsg for details.
+// Returns:
+// 	0     - success
+// 	EBADF - listener is not a valid tailscale_listener
+// 	-1    - call tailscale_errmsg for details
 extern int tailscale_listener_close(tailscale_listener listener);
 
 // tailscale_accept accepts a connection on a tailscale_listener.
diff --git a/tsnetctest/tsnetctest.go b/tsnetctest/tsnetctest.go
index 371cab6..e386c0f 100644
--- a/tsnetctest/tsnetctest.go
+++ b/tsnetctest/tsnetctest.go
@@ -112,6 +112,10 @@ int test_conn() {
 	if ((ret = tailscale_listener_close(ln)) != 0) {
 		return set_err(s1, 'a');
 	}
+	if ((ret = tailscale_listener_close(ln)) != EBADF) {
+		snprintf(err, errlen, "double tailscale_listener_close = %d (%s), want EBADF", errno, strerror(errno));
+		return 1;
+	}
 
 	if ((ret = tailscale_loopback(s1, addr, addrlen, proxy_cred, local_api_cred)) != 0) {
 		return set_err(s1, 'b');