diff --git a/.travis.yml b/.travis.yml
index bc17c2a..360bc0d 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -12,6 +12,11 @@ env:
     - LIBZOOKEEPER_VERSION=3.5.9
     - LIBZOOKEEPER_VERSION=3.4.14
 
+jobs:
+    include:
+        - dist: bionic
+          php: 8.1.0
+
 addons:
   apt:
     packages:
diff --git a/package.xml b/package.xml
index 39a351c..64e5555 100644
--- a/package.xml
+++ b/package.xml
@@ -78,7 +78,7 @@ Improvements:
   <required>
    <php>
     <min>7.0.0</min>
-    <max>8.0.99</max>
+    <max>8.1.99</max>
    </php>
    <pearinstaller>
     <min>1.4.0b1</min>
diff --git a/tests/exists_with_invalid_param.phpt b/tests/exists_with_invalid_param.phpt
index 2a5ce41..c2ad063 100644
--- a/tests/exists_with_invalid_param.phpt
+++ b/tests/exists_with_invalid_param.phpt
@@ -13,6 +13,6 @@ files/exists_with_invalid_param.inc
 --EXPECTF--
 Fatal error: Uncaught TypeError: Zookeeper::exists(): Argument #2 ($watcher_cb) must be a valid callback or null, no array or string given in %s:%d
 Stack trace:
-#0 %s(%d): Zookeeper->exists('/test', 1)
+#0 %s(%d): Zookeeper->exists('/test', %f)
 #1 {main}
   thrown in %s on line %d