diff --git a/packages/ketcher-core/src/domain/entities/RNABase.ts b/packages/ketcher-core/src/domain/entities/RNABase.ts
index 8c8c99815b..c81f88e094 100644
--- a/packages/ketcher-core/src/domain/entities/RNABase.ts
+++ b/packages/ketcher-core/src/domain/entities/RNABase.ts
@@ -1,11 +1,11 @@
 import { BaseMonomer } from 'domain/entities/BaseMonomer';
 
 export class RNABase extends BaseMonomer {
-  public getValidSourcePoint(monomer: BaseMonomer) {
-    return monomer.firstFreeAttachmentPoint;
+  public getValidSourcePoint(_monomer: BaseMonomer) {
+    return this.firstFreeAttachmentPoint;
   }
 
-  public getValidTargetPoint(monomer: BaseMonomer) {
-    return monomer.firstFreeAttachmentPoint;
+  public getValidTargetPoint(_monomer: BaseMonomer) {
+    return this.firstFreeAttachmentPoint ;
   }
 }