diff --git a/testdata/parser/negative/17.pdl b/testdata/parser/negative/17.pdl
new file mode 100644
index 0000000000000000000000000000000000000000..28b1bd0f9f9ebd0b8ea3870edc4c37851a591e3a
--- /dev/null
+++ b/testdata/parser/negative/17.pdl
@@ -0,0 +1,8 @@
+#version 100
+
+// illegal assignment
+primitive main(in a, out b) {
+	int x = 0;
+	int y = 0;
+	x + y = 0;
+}
\ No newline at end of file