diff --git a/src/main/java/de/svenkubiak/jpushover/http/PushoverRequest.java b/src/main/java/de/svenkubiak/jpushover/http/PushoverRequest.java
index d581a9c..41b7889 100644
--- a/src/main/java/de/svenkubiak/jpushover/http/PushoverRequest.java
+++ b/src/main/java/de/svenkubiak/jpushover/http/PushoverRequest.java
@@ -48,9 +48,11 @@ public class PushoverRequest {
                 .timeout(Duration.ofSeconds(5))
                 .header("Content-Type", "application/json")
                 .POST(HttpRequest.BodyPublishers.ofString(body))
+                .version(HttpClient.Version.HTTP_1_1)
                 .build();
 
         var httpClientBuilder = HttpClient.newBuilder();
+        httpClientBuilder.version(HttpClient.Version.HTTP_1_1);
 
         if (proxyHost != null && proxyPort > 0) {
             httpClientBuilder.proxy(ProxySelector.of(new InetSocketAddress(proxyHost, proxyPort)));