diff --git a/diktat-rules/src/test/kotlin/org/cqfn/diktat/util/FixTestBase.kt b/diktat-rules/src/test/kotlin/org/cqfn/diktat/util/FixTestBase.kt
index 83e310e62d..d72d8eb658 100644
--- a/diktat-rules/src/test/kotlin/org/cqfn/diktat/util/FixTestBase.kt
+++ b/diktat-rules/src/test/kotlin/org/cqfn/diktat/util/FixTestBase.kt
@@ -204,7 +204,7 @@ open class FixTestBase(
     }
 
     companion object {
-        private val saveVersion = "0.3.1"
-        private val ktlintVersion = "0.46.1"
+        private const val saveVersion = "0.3.1"
+        private const val ktlintVersion = "0.46.1"
     }
 }