diff --git a/src/main/kotlin/org/phoenixframework/Transport.kt b/src/main/kotlin/org/phoenixframework/Transport.kt
index 25c8818..738fad6 100644
--- a/src/main/kotlin/org/phoenixframework/Transport.kt
+++ b/src/main/kotlin/org/phoenixframework/Transport.kt
@@ -155,6 +155,7 @@ class WebSocketTransport(
 
   override fun onClosing(webSocket: WebSocket, code: Int, reason: String) {
     this.readyState = Transport.ReadyState.CLOSING
+    webSocket.close(code, reason)
   }
 
   override fun onMessage(webSocket: WebSocket, text: String) {
diff --git a/src/test/kotlin/org/phoenixframework/WebSocketTransportTest.kt b/src/test/kotlin/org/phoenixframework/WebSocketTransportTest.kt
index 381b5ed..b9a7846 100644
--- a/src/test/kotlin/org/phoenixframework/WebSocketTransportTest.kt
+++ b/src/test/kotlin/org/phoenixframework/WebSocketTransportTest.kt
@@ -136,6 +136,7 @@ class WebSocketTransportTest {
       transport.readyState = Transport.ReadyState.OPEN
 
       transport.onClosing(mockWebSocket, 10, "reason")
+      verify(mockWebSocket).close(10, "reason")
       assertThat(transport.readyState).isEqualTo(Transport.ReadyState.CLOSING)
     }