nullstring
diff --git a/‎lib/less/extend-visitor.js
Lines changed: 13 additions & 2 deletions b/‎lib/less/extend-visitor.js
Lines changed: 13 additions & 2 deletions
diff --git a/‎test/css/extend-chaining.css
Lines changed: 15 additions & 0 deletions b/‎test/css/extend-chaining.css
Lines changed: 15 additions & 0 deletions
diff --git a/‎test/less/errors/extend-circular.less
Lines changed: 0 additions & 26 deletions b/‎test/less/errors/extend-circular.less
Lines changed: 0 additions & 26 deletions
diff --git a/‎test/less/errors/extend-circular.txt
Lines changed: 0 additions & 2 deletions b/‎test/less/errors/extend-circular.txt
Lines changed: 0 additions & 2 deletions
diff --git a/‎test/less/extend-chaining.less
Lines changed: 13 additions & 1 deletion b/‎test/less/extend-chaining.less
Lines changed: 13 additions & 1 deletion
@@ -109,7 +109,7 @@
                             newSelector[newSelector.length-1].extendList = [newExtend];
                             extendsToAdd.push(newExtend);
                             newExtend.ruleset = targetExtend.ruleset;
-                            newExtend.parent = targetExtend;
+                            newExtend.parents = [targetExtend, extend];
                             targetExtend.ruleset.paths.push(newSelector);
                         });
                     }
@@ -135,7 +135,18 @@
             }
         },
         inInheritanceChain: function (possibleParent, possibleChild) {
-            return possibleParent === possibleChild || (possibleChild.parent ? this.inInheritanceChain(possibleParent, possibleChild.parent) : false);
+            if (possibleParent === possibleChild) {
+                return true;
+            }
+            if (possibleChild.parents) {
+                if (this.inInheritanceChain(possibleParent, possibleChild.parents[0])) {
+                    return true;
+                }
+                if (this.inInheritanceChain(possibleParent, possibleChild.parents[1])) {
+                    return true;
+                }
+            }
+            return false;
         },
         visitRule: function (ruleNode, visitArgs) {
             visitArgs.visitDeeper = false;
 
@@ -36,3 +36,18 @@
 .v.w.v {
   color: black;
 }
+.x,
+.y,
+.z {
+  color: x;
+}
+.y,
+.z,
+.x {
+  color: y;
+}
+.z,
+.x,
+.y {
+  color: z;
+}
@@ -45,4 +45,16 @@
 // circular reference because the new extend product will match the existing extend
 
 .w:extend(.w) {color: black;}
-.v.w.v:extend(.w all){}
+.v.w.v:extend(.w all){}
+
+// classic circular references
+
+.x:extend(.z) {
+  color: x;
+}
+.y:extend(.x) {
+  color: y;
+}
+.z:extend(.y) {
+  color: z;
+}