diff --git a/dao/src/test/java/org/thingsboard/server/dao/service/BaseDeviceCredentialsCacheTest.java b/dao/src/test/java/org/thingsboard/server/dao/service/BaseDeviceCredentialsCacheTest.java
index 9415da99ea..7fc9f7b218 100644
--- a/dao/src/test/java/org/thingsboard/server/dao/service/BaseDeviceCredentialsCacheTest.java
+++ b/dao/src/test/java/org/thingsboard/server/dao/service/BaseDeviceCredentialsCacheTest.java
@@ -43,8 +43,8 @@ import static org.mockito.Mockito.when;
 
 public abstract class BaseDeviceCredentialsCacheTest extends AbstractServiceTest {
 
-    private static final String CREDENTIALS_ID_1 = StringUtils.randomAlphanumeric(20);
-    private static final String CREDENTIALS_ID_2 = StringUtils.randomAlphanumeric(20);
+    private final String CREDENTIALS_ID_1 = StringUtils.randomAlphanumeric(20);
+    private final String CREDENTIALS_ID_2 = StringUtils.randomAlphanumeric(20);
 
     @Autowired
     private DeviceCredentialsService deviceCredentialsService;