diff --git a/web/app/brep/operations/boolean.js b/web/app/brep/operations/boolean.js
index 17656864..47ec369e 100644
--- a/web/app/brep/operations/boolean.js
+++ b/web/app/brep/operations/boolean.js
@@ -66,8 +66,13 @@ function checkShellForErrors(shell, code) {
   }
 }
 
-export function BooleanAlgorithm( shellA, shellB, type ) {
+let EDGE_REPLACE = [];
 
+export function BooleanAlgorithm( shellA, shellB, type ) {
+  
+  //fixme
+  EDGE_REPLACE = [];
+  
   BREP_DEBUG.startBooleanSession(shellA, shellB, type);
 
   shellA = prepareWorkingCopy(shellA);
@@ -93,6 +98,8 @@ export function BooleanAlgorithm( shellA, shellB, type ) {
 
   intersectFaces(shellA, shellB, type);
 
+  replaceEdges();
+  
   replaceMergedFaces(facesData, mergedFaces);
   for (let faceData of facesData) {
     faceData.initGraph();
@@ -154,6 +161,12 @@ function removeInvalidLoops(facesData) {
   }
 }
 
+function replaceEdges() {
+  for (let {from, to} of EDGE_REPLACE) {
+    from.replace(to);
+  }
+}
+
 function replaceMergedFaces(facesData, mergedFaces) {
   filterInPlace(facesData, ({face}) => 
       mergedFaces.find(({originFaces}) => originFaces.indexOf(face) > -1) === undefined
@@ -332,6 +345,7 @@ function mergeFaces(facesA, facesB, opType) {
         }
         if (isSameEdge(testee, edge)) {
           //annihilation here
+          markEdgeToReplace(testee, edge.twin());
           invalid.add(testee);
           invalid.add(edge);
         }
@@ -459,6 +473,10 @@ function mergeFaces(facesA, facesB, opType) {
   };
 }
 
+function markEdgeToReplace(from, to) {
+  EDGE_REPLACE.push({from, to});
+}
+
 export function mergeVertices(shell1, shell2) {
   const toSwap = new Map();
   for (let v1 of shell1.vertices) {
@@ -656,7 +674,6 @@ function newEdgeDirectionValidityTest(e, curve) {
 }
 
 function intersectFaces(shellA, shellB, operationType) {
-  const invert = operationType === TYPE.UNION;
   for (let i = 0; i < shellA.faces.length; i++) {
     const faceA = shellA.faces[i];
     if (DEBUG.FACE_FACE_INTERSECTION) {
diff --git a/web/app/brep/topo/edge.js b/web/app/brep/topo/edge.js
index 881eb327..8ebac42d 100644
--- a/web/app/brep/topo/edge.js
+++ b/web/app/brep/topo/edge.js
@@ -78,4 +78,21 @@ class HalfEdge extends TopoObject {
     }
     return res;
   }
+  
+  replace(he) {
+    if (this.edge.halfEdge1 === this) {
+      this.edge.halfEdge1 = he;
+    } else {
+      this.edge.halfEdge2 = he;
+    }
+
+    he.edge = this.edge;
+    he.loop = this.loop;
+    
+    he.prev = this.prev;
+    he.prev.next = he;
+
+    he.next = this.next;
+    he.next.prev = he;
+  }
 }