diff --git a/js/src/jit-test/tests/gc/bug-1779833.js b/js/src/jit-test/tests/gc/bug-1779833.js
new file mode 100644
index 000000000000..7b2f13204604
--- /dev/null
+++ b/js/src/jit-test/tests/gc/bug-1779833.js
@@ -0,0 +1,20 @@
+// This failed when run under ASAN.
+
+let size = 6;
+
+let map = new Map();
+assertEq(isNurseryAllocated(map), true);
+for (let i = 0; i < size; i++) {
+  map.set(i, {});
+}
+
+for (let i = 0; i < size - 1; i++) {
+  map.delete(i);
+}
+
+for (let i = 0; i < size - 1; i++) {
+  map.set(i, {});
+}
+
+map = undefined;
+minorgc();