diff --git a/src/cmd/compile/internal/gc/ssa.go b/src/cmd/compile/internal/gc/ssa.go
index 8f615908644..4aca79307ad 100644
--- a/src/cmd/compile/internal/gc/ssa.go
+++ b/src/cmd/compile/internal/gc/ssa.go
@@ -3205,7 +3205,7 @@ func (s *state) canSSA(n *Node) bool {
 			return false
 		}
 	}
-	if n.Class == PPARAM && n.String() == ".this" {
+	if n.Class == PPARAM && n.Sym != nil && n.Sym.Name == ".this" {
 		// wrappers generated by genwrapper need to update
 		// the .this pointer in place.
 		// TODO: treat as a PPARMOUT?