diff --git a/cue/build.go b/cue/build.go
index bdaf00f..2ea58e8 100644
--- a/cue/build.go
+++ b/cue/build.go
@@ -193,25 +193,19 @@
 	})
 }
 
-type importIndex map[*build.Instance]*Instance
-
 // index maps conversions from label names to internal codes.
 //
 // All instances belonging to the same package should share this index.
 type index struct {
 	*runtime.Runtime
-	loaded importIndex
+	loaded map[*build.Instance]*Instance
 }
 
 // NewRuntime creates a *runtime.Runtime with builtins preloaded.
 func NewRuntime() *runtime.Runtime {
-	r := runtime.New()
-	i := &index{
-		Runtime: r,
-		loaded:  importIndex{},
-	}
-	r.Data = i
-	return r
+	i := newIndex()
+	i.Runtime.Data = i
+	return i.Runtime
 }
 
 // newIndex creates a new index.
@@ -219,7 +213,7 @@
 	r := runtime.New()
 	i := &index{
 		Runtime: r,
-		loaded:  importIndex{},
+		loaded:  map[*build.Instance]*Instance{},
 	}
 	r.Data = i
 	return i
@@ -230,6 +224,6 @@
 }
 
 func (idx *index) loadInstance(p *build.Instance) *Instance {
-	idx.Runtime.Build(p)
-	return idx.getImportFromBuild(p)
+	v, _ := idx.Runtime.Build(p)
+	return idx.getImportFromBuild(p, v)
 }
diff --git a/cue/instance.go b/cue/instance.go
index d5b43f3..53bc5d6 100644
--- a/cue/instance.go
+++ b/cue/instance.go
@@ -59,18 +59,13 @@
 	return p
 }
 
-func (x *index) getImportFromBuild(p *build.Instance) *Instance {
+func (x *index) getImportFromBuild(p *build.Instance, v *adt.Vertex) *Instance {
 	inst := x.loaded[p]
 
 	if inst != nil {
 		return inst
 	}
 
-	v := x.GetNodeFromInstance(p)
-	if v == nil {
-		return nil
-	}
-
 	inst = &Instance{
 		ImportPath:  p.ImportPath,
 		Dir:         p.Dir,
@@ -95,7 +90,7 @@
 		return nil
 	}
 
-	return x.getImportFromBuild(p)
+	return x.getImportFromBuild(p, v)
 }
 
 func (x *index) getImportFromPath(id string) *Instance {
diff --git a/cue/types.go b/cue/types.go
index b85cfbf..e78c41f 100644
--- a/cue/types.go
+++ b/cue/types.go
@@ -1857,7 +1857,7 @@
 	if v.v == nil {
 		return nil
 	}
-	return v.ctx().getImportFromNode(v.v)
+	return v.idx.getImportFromNode(v.v)
 }
 
 // Reference returns the instance and path referred to by this value such that
diff --git a/internal/core/runtime/build.go b/internal/core/runtime/build.go
index c167e16..0927071 100644
--- a/internal/core/runtime/build.go
+++ b/internal/core/runtime/build.go
@@ -28,7 +28,7 @@
 // Build builds b and all its transitive dependencies, insofar they have not
 // been build yet.
 func (x *Runtime) Build(b *build.Instance) (v *adt.Vertex, errs errors.Error) {
-	if v := x.GetNodeFromInstance(b); v != nil {
+	if v := x.getNodeFromInstance(b); v != nil {
 		return v, b.Err
 	}
 	// TODO: clear cache of old implementation.
diff --git a/internal/core/runtime/imports.go b/internal/core/runtime/imports.go
index 4f25c96..97f718d 100644
--- a/internal/core/runtime/imports.go
+++ b/internal/core/runtime/imports.go
@@ -95,7 +95,7 @@
 	return r.index.imports[key]
 }
 
-func (r *Runtime) GetNodeFromInstance(key *build.Instance) *adt.Vertex {
+func (r *Runtime) getNodeFromInstance(key *build.Instance) *adt.Vertex {
 	return r.index.importsByBuild[key]
 }