diff --git a/cc/stl.go b/cc/stl.go
index 4f8865f..75921c6 100644
--- a/cc/stl.go
+++ b/cc/stl.go
@@ -62,6 +62,8 @@
 		s := ""
 		if stl.Properties.Stl != nil {
 			s = *stl.Properties.Stl
+		} else if ctx.header() {
+			s = "none"
 		}
 		if ctx.useSdk() && ctx.Device() {
 			switch s {