diff --git a/cue/testdata/eval/issue3301.txtar b/cue/testdata/eval/issue3301.txtar
new file mode 100644
index 00000000000..16948954083
--- /dev/null
+++ b/cue/testdata/eval/issue3301.txtar
@@ -0,0 +1,77 @@
+-- in.cue --
+object: #Leaf & {}
+
+#Base: {
+	extra?: {...}
+}
+
+#Mid: {
+	#Base
+}
+
+#Leaf: {
+	#Mid
+	extra?:  {...}
+	more?: int
+	if extra.foo != _|_ {
+		if more != _|_ {
+			foo: "bar"
+		}
+	}
+}
+-- out/eval --
+(struct){
+  object: (#struct){
+    extra?: (#struct){
+    }
+    more?: (int){ int }
+  }
+  #Base: (#struct){
+    extra?: (#struct){
+    }
+  }
+  #Mid: (#struct){
+    extra?: (#struct){
+    }
+  }
+  #Leaf: (#struct){
+    extra?: (#struct){
+    }
+    more?: (int){ int }
+  }
+}
+-- out/eval/stats --
+Leaks:  0
+Freed:  11
+Reused: 5
+Allocs: 6
+Retain: 7
+
+Unifications: 11
+Conjuncts:    25
+Disjuncts:    18
+-- out/compile --
+--- in.cue
+{
+  object: (〈0;#Leaf〉 & {})
+  #Base: {
+    extra?: {
+      ...
+    }
+  }
+  #Mid: {
+    〈1;#Base〉
+  }
+  #Leaf: {
+    〈1;#Mid〉
+    extra?: {
+      ...
+    }
+    more?: int
+    if (〈0;extra〉.foo != _|_(explicit error (_|_ literal) in source)) {
+      if (〈1;more〉 != _|_(explicit error (_|_ literal) in source)) {
+        foo: "bar"
+      }
+    }
+  }
+}
diff --git a/internal/core/adt/fields.go b/internal/core/adt/fields.go
index ea40ec1cc83..08620a2fa2b 100644
--- a/internal/core/adt/fields.go
+++ b/internal/core/adt/fields.go
@@ -433,17 +433,28 @@ func (cc *closeContext) linkNotify(ctx *OpContext, dst *Vertex, key *closeContex
 func (cc *closeContext) assignConjunct(ctx *OpContext, root *closeContext, c Conjunct, mode ArcType, check, checkClosed bool) (arc *closeContext, pos int, added bool) {
 	arc = cc.getKeyedCC(ctx, root, c.CloseInfo.CycleInfo, mode, checkClosed)
 
-	pos = len(*arc.group)
-
 	c.CloseInfo.cc = nil
-	added = !check || !hasConjunct(*arc.group, c)
+
+	var group ConjunctGroup
+	if arc.group != nil {
+		group = *arc.group
+	}
+	pos = len(group)
+
+	added = !check || !hasConjunct(group, c)
 	if added {
 		c.CloseInfo.cc = arc
 
 		if c.CloseInfo.cc.src != arc.src {
 			panic("Inconsistent src")
 		}
-		*arc.group = append(*arc.group, c)
+
+		group = append(group, c)
+		if arc.group == nil {
+			arc.group = &group
+		} else {
+			*arc.group = group
+		}
 	}
 
 	return arc, pos, added