diff --git a/src/extensions/dnatco/confal-pyramids/util.ts b/src/extensions/dnatco/confal-pyramids/util.ts
index 6dc100cab5c3f66fd43c7b6bb66182b5cb1038f4..f30784b80b27bb4cec0963028fe9386d76df8fb8 100644
--- a/src/extensions/dnatco/confal-pyramids/util.ts
+++ b/src/extensions/dnatco/confal-pyramids/util.ts
@@ -87,6 +87,8 @@ export class ConfalPyramidsIterator {
             return this.moveStep();
         } else {
             this.residueIt.setSegment(this.chainIt.move());
+            if (this.residueIt.hasNext)
+                this.residueTwo = this.residueIt.move();
             return this.moveStep();
         }
     }