diff --git a/build.gradle b/build.gradle
index 3996243..72358cb 100644
--- a/build.gradle
+++ b/build.gradle
@@ -11,7 +11,7 @@ apply plugin: 'signing'
 apply from: "gradle/integrationTest.gradle"
 
 group = 'de.undercouch'
-version = '5.6.0'
+version = '5.6.1'
 
 java {
     sourceCompatibility = '1.8'
@@ -30,7 +30,9 @@ ext {
             "5.6.4",
             "6.9.4",
             "7.6.4",
-            "8.6"
+            "8.6",
+            "8.7",
+            "8.8"
         ]
     } else {
         limitedVersionsToTest = versionsToTest
@@ -189,6 +191,11 @@ tasks.withType(Sign).configureEach {
             return false
         }
 
+        // don't attempt to sign without a key
+        if (!project.hasProperty('signing.keyId')) {
+            return false
+        }
+
         return true
     }
 }
diff --git a/gradle/integrationTest.gradle b/gradle/integrationTest.gradle
index f117e29..9e6a537 100644
--- a/gradle/integrationTest.gradle
+++ b/gradle/integrationTest.gradle
@@ -33,7 +33,7 @@ ext {
         '7.5', '7.5.1', '7.6', '7.6.1', '7.6.2', '7.6.3', '7.6.4',
 
         '8.0', '8.0.1', '8.0.2', '8.1', '8.1.1', '8.2', '8.2.1', '8.3', '8.4',
-        '8.5', '8.6'
+        '8.5', '8.6', '8.7', '8.8'
     ]
 }
 
diff --git a/gradle/wrapper/gradle-wrapper.properties b/gradle/wrapper/gradle-wrapper.properties
index a80b22c..a441313 100644
--- a/gradle/wrapper/gradle-wrapper.properties
+++ b/gradle/wrapper/gradle-wrapper.properties
@@ -1,6 +1,6 @@
 distributionBase=GRADLE_USER_HOME
 distributionPath=wrapper/dists
-distributionUrl=https\://services.gradle.org/distributions/gradle-8.6-bin.zip
+distributionUrl=https\://services.gradle.org/distributions/gradle-8.8-bin.zip
 networkTimeout=10000
 validateDistributionUrl=true
 zipStoreBase=GRADLE_USER_HOME
diff --git a/settings.gradle b/settings.gradle
new file mode 100644
index 0000000..e69de29