diff --git a/testdata/parser/positive/12.pdl b/testdata/parser/positive/12.pdl
new file mode 100644
index 0000000000000000000000000000000000000000..1ac91cd80217398a5d0b89f821a4a03c521ff563
--- /dev/null
+++ b/testdata/parser/positive/12.pdl
@@ -0,0 +1,14 @@
+#version 100
+
+primitive main(in a, out b) {
+	int x = 0;
+	int y = 0;
+	x += y + 5;
+	y %= x -= 3;
+	x *= x * (x *= 5);
+	while (true) {
+		synchronous {
+			assert fires(a) == fires(b);
+		}
+	}
+}
\ No newline at end of file