diff --git a/build.gradle b/build.gradle
index c88890d..4f7affd 100644
--- a/build.gradle
+++ b/build.gradle
@@ -1,6 +1,6 @@
 plugins {
     id 'java'
-    id 'org.springframework.boot' version '3.3.6'
+    id 'org.springframework.boot' version '4.0.5'
     id 'io.spring.dependency-management' version '1.1.7'
     id 'checkstyle'
     id 'com.github.spotbugs' version '6.4.8'
diff --git a/src/test/java/com/example/temporal/workflows/http/HttpActivitiesTest.java b/src/test/java/com/example/temporal/workflows/http/HttpActivitiesTest.java
index b69a6ae..95bfe08 100644
--- a/src/test/java/com/example/temporal/workflows/http/HttpActivitiesTest.java
+++ b/src/test/java/com/example/temporal/workflows/http/HttpActivitiesTest.java
@@ -55,7 +55,7 @@ void testHttpGet_Success() {
   void testHttpGet_EmptyResponse() {
     // Arrange
     String url = "https://example.com";
-    ResponseEntity<String> responseEntity = new ResponseEntity<>(null, HttpStatus.OK);
+    ResponseEntity<String> responseEntity = new ResponseEntity<>((String) null, HttpStatus.OK);
 
     when(restTemplate.getForEntity(url, String.class)).thenReturn(responseEntity);