diff --git a/vlib/compiler/expression.v b/vlib/compiler/expression.v
index 6de9755ded..b339c31d6c 100644
--- a/vlib/compiler/expression.v
+++ b/vlib/compiler/expression.v
@@ -187,7 +187,10 @@ fn (p mut Parser) name_expr() string {
 		p.check(.dot)
 		name = p.lit
 		// C struct initialization
-		if p.peek() == .lcbr && p.table.known_type(name) {
+		if p.peek() == .lcbr {
+			if !p.table.known_type(name) {
+				p.error('unknown C type `$name`')
+			}
 			return p.get_struct_type(name, true, ptr)
 		}
 		if ptr && p.peek() == .lpar {