diff --git a/tests/micropython/heapalloc_bytesio.py b/tests/micropython/heapalloc_bytesio.py
new file mode 100644
index 0000000000..3116328518
--- /dev/null
+++ b/tests/micropython/heapalloc_bytesio.py
@@ -0,0 +1,13 @@
+import uio
+import micropython
+
+data = b"1234" * 16
+buf = uio.BytesIO(64)
+
+micropython.heap_lock()
+
+buf.write(data)
+
+micropython.heap_unlock()
+
+print(buf.getvalue())
diff --git a/tests/micropython/heapalloc_bytesio.py.exp b/tests/micropython/heapalloc_bytesio.py.exp
new file mode 100644
index 0000000000..675761c2bb
--- /dev/null
+++ b/tests/micropython/heapalloc_bytesio.py.exp
@@ -0,0 +1 @@
+b'1234123412341234123412341234123412341234123412341234123412341234'