diff --git a/tests/basics/slice_op.py b/tests/basics/slice_op.py
index f1e83c5e2..0bb6e365b 100644
--- a/tests/basics/slice_op.py
+++ b/tests/basics/slice_op.py
@@ -1,3 +1,5 @@
+# Test slice unary operations.
+# CPython allows hashing slices, but MicroPython does not.
 
 try:
     t = [][:]
diff --git a/tests/basics/slice_op.py.exp b/tests/basics/slice_op.py.exp
new file mode 100644
index 000000000..6002b71c5
--- /dev/null
+++ b/tests/basics/slice_op.py.exp
@@ -0,0 +1 @@
+TypeError