diff --git a/src/go/internal/gcimporter/ureader.go b/src/go/internal/gcimporter/ureader.go
index dacc161ec8..15c8c2032d 100644
--- a/src/go/internal/gcimporter/ureader.go
+++ b/src/go/internal/gcimporter/ureader.go
@@ -31,6 +31,10 @@ type pkgReader struct {
 	laterFns []func()
 	// laterFors is used in case of 'type A B' to ensure that B is processed before A.
 	laterFors map[types.Type]int
+
+	// ifaces holds a list of constructed Interfaces, which need to have
+	// Complete called after importing is done.
+	ifaces []*types.Interface
 }
 
 // later adds a function to be invoked at the end of import reading.
@@ -86,6 +90,10 @@ func readUnifiedPackage(fset *token.FileSet, ctxt *types.Context, imports map[st
 		fn()
 	}
 
+	for _, iface := range pr.ifaces {
+		iface.Complete()
+	}
+
 	pkg.MarkComplete()
 	return pkg
 }
@@ -386,6 +394,16 @@ func (r *reader) interfaceType() *types.Interface {
 	if implicit {
 		iface.MarkImplicit()
 	}
+
+	// We need to call iface.Complete(), but if there are any embedded
+	// defined types, then we may not have set their underlying
+	// interface type yet. So we need to defer calling Complete until
+	// after we've called SetUnderlying everywhere.
+	//
+	// TODO(mdempsky): After CL 424876 lands, it should be safe to call
+	// iface.Complete() immediately.
+	r.p.ifaces = append(r.p.ifaces, iface)
+
 	return iface
 }