diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index 26820aa..6b5f965 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -1,4 +1,4 @@
-image: gradle:alpine
+image: gradle:7-jdk11
 
 variables:
   GRADLE_OPTS: "-Dorg.gradle.daemon=false"
diff --git a/examples/build.gradle.kts b/examples/build.gradle.kts
index 0e74114..65e25ae 100644
--- a/examples/build.gradle.kts
+++ b/examples/build.gradle.kts
@@ -26,7 +26,7 @@ tasks {
     register("runJava", JavaExec::class) {
         group = "application"
         main = "com.example.BitlySample"
-        classpath = sourceSets["main"].runtimeClasspath
+        classpath = sourceSets.main.get().runtimeClasspath
     }
 
     register("runRetrieve", JavaExec::class) {