diff --git a/vlib/v/gen/c/cgen.v b/vlib/v/gen/c/cgen.v
index a971ec20ac..f7a19c3391 100644
--- a/vlib/v/gen/c/cgen.v
+++ b/vlib/v/gen/c/cgen.v
@@ -2679,6 +2679,10 @@ fn (mut g Gen) autofree_scope_vars2(scope &ast.Scope, start_pos int, end_pos int
 }
 
 fn (mut g Gen) autofree_variable(v ast.Var) {
+	// filter out invalid variables
+	if v.typ == 0 {
+		return
+	}
 	sym := g.table.sym(v.typ)
 	// if v.name.contains('output2') {
 	if g.is_autofree {