diff --git a/testdata/parser/negative/28.txt b/testdata/parser/negative/28.txt
new file mode 100644
index 0000000000000000000000000000000000000000..89580285f2fba602ae3df5d471ab293c29481eee
--- /dev/null
+++ b/testdata/parser/negative/28.txt
@@ -0,0 +1,3 @@
+Parse error at 28.pdl:5:8: Unassignable expression
+    (x + 5)++; // not assignable
+       ^