diff --git a/test/libsolidity/semanticTests/operators/compound_assignment_evaluation_order_and_single_eval.sol b/test/libsolidity/semanticTests/operators/compound_assignment_evaluation_order_and_single_eval.sol
new file mode 100644
index 000000000000..aa982ed68dc4
--- /dev/null
+++ b/test/libsolidity/semanticTests/operators/compound_assignment_evaluation_order_and_single_eval.sol
@@ -0,0 +1,30 @@
+// Pins down evaluation order and single-evaluation for indexed
+// (compound) assignment:
+//   - In `a[f()] = g()`, the RHS `g()` is evaluated before the LHS
+//     index `f()`, so RHS side effects are observable when the index
+//     is computed.
+//   - In `a[f()] += v`, the LHS index `f()` is evaluated exactly once;
+//     the slot computation is not re-evaluated for the write side.
+contract C {
+    uint[2] public a;
+    uint public counter;
+
+    function bumpIdx() internal returns (uint) {
+        counter += 1;
+        return counter - 1;
+    }
+
+    function calculateVal() internal returns (uint) {
+        return 10 * (counter + 100);
+    }
+
+    function run() public returns (uint c, uint a0, uint a1) {
+        a[bumpIdx()] = calculateVal();
+        a[bumpIdx()] = calculateVal();
+        c = counter;
+        a0 = a[0];
+        a1 = a[1];
+    }
+}
+// ----
+// run() -> 2, 1000, 1010