diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index ae04a23f..ebd008aa 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -1,7 +1,7 @@
 [versions]
 slf4jVersion = "2.0.17"
 junitVersion = "4.13.2"
-junitBomVersion = "5.13.4"
+junitBomVersion = "6.0.0"
 equalsVerifierVersion = "4.1.1"
 purefunVersion = "5.1"
 purejsonVersion = "1.1"
diff --git a/junit5/src/main/java/com/github/tonivade/zeromock/junit5/MockHttpServerExtension.java b/junit5/src/main/java/com/github/tonivade/zeromock/junit5/MockHttpServerExtension.java
index 6128d9ce..4429f3a2 100644
--- a/junit5/src/main/java/com/github/tonivade/zeromock/junit5/MockHttpServerExtension.java
+++ b/junit5/src/main/java/com/github/tonivade/zeromock/junit5/MockHttpServerExtension.java
@@ -116,15 +116,23 @@ private List<Tuple2<Field, Mount>> findServices(ExtensionContext extensionContex
   }
 
   private HttpServer createMockServer(ExtensionContext context) {
-    return getStore(context).getOrComputeIfAbsent(SERVER, key -> buildMockServer(context), HttpServer.class);
+    return getStore(context).computeIfAbsent(SERVER, key -> buildMockServer(context), HttpServer.class);
   }
 
   private HttpServer getMockServer(ExtensionContext context) {
-    return getStore(context).get(SERVER, HttpServer.class);
+    var httpServer = getStore(context).get(SERVER, HttpServer.class);
+    if (httpServer == null) {
+      throw new IllegalStateException();
+    }
+    return httpServer;
   }
 
   private HttpServer removeMockServer(ExtensionContext context) {
-    return getStore(context).remove(SERVER, HttpServer.class);
+    var httpServer = getStore(context).remove(SERVER, HttpServer.class);
+    if (httpServer == null) {
+      throw new IllegalStateException();
+    }
+    return httpServer;
   }
 
   private Store getStore(ExtensionContext context) {