diff --git a/src/cmd/compile/internal/gc/sinit.go b/src/cmd/compile/internal/gc/sinit.go
index 6b3c426ca3..416e2b252b 100644
--- a/src/cmd/compile/internal/gc/sinit.go
+++ b/src/cmd/compile/internal/gc/sinit.go
@@ -585,7 +585,7 @@ func isliteral(n *Node) bool {
 }
 
 func (n *Node) isSimpleName() bool {
-	return n.Op == ONAME && n.Addable && n.Class != PAUTOHEAP
+	return n.Op == ONAME && n.Addable && n.Class != PAUTOHEAP && n.Class != PEXTERN
 }
 
 func litas(l *Node, r *Node, init *Nodes) {
diff --git a/test/writebarrier.go b/test/writebarrier.go
index 6460a6f9da..13f7b54608 100644
--- a/test/writebarrier.go
+++ b/test/writebarrier.go
@@ -220,3 +220,19 @@ func f22(x *int) (y *int) {
 	*p = x // no barrier
 	return
 }
+
+type T23 struct {
+	p *int
+	a int
+}
+
+var t23 T23
+var i23 int
+
+func f23() {
+	// zeroing global needs write barrier for the hybrid barrier.
+	t23 = T23{} // ERROR "write barrier"
+	// also test partial assignments
+	t23 = T23{a: 1}    // ERROR "write barrier"
+	t23 = T23{p: &i23} // ERROR "write barrier"
+}