diff --git a/tests/test_reconcile.py b/tests/test_reconcile.py
index b7085a3b30515dc7597ce24e4f92f21d93a72b47..48835b19d0f64bb3881349b0d52086eadea090c0 100644
--- a/tests/test_reconcile.py
+++ b/tests/test_reconcile.py
@@ -308,3 +308,21 @@ def test_subset_sum_match():
         [],  # No remaining statement trans.
         [],  # No remaining books trans.
     )
+
+def test_subset_passes_through_all_non_matches():
+    """This was used to locate a bug where some of the non-matches had
+    gone missing due to mutation of books_trans."""
+    statement_trans = [
+        S1,  # No match
+        S4,  # Match
+    ]
+    books_trans = [
+        B2,  # No match
+        B4A, B4B, B4C, # Match
+        B3_next_day, B3_next_week,  # No match
+    ]
+    assert subset_match(statement_trans, books_trans) == (
+        [([S4], [B4A, B4B, B4C], [])],  # Matched
+        [S1],  # No match: preserved intact
+        [B2, B3_next_day, B3_next_week]  # No match: preserved intact
+    )