diff --git a/quasardb/numpy/__init__.py b/quasardb/numpy/__init__.py
index cab194cc..32479995 100644
--- a/quasardb/numpy/__init__.py
+++ b/quasardb/numpy/__init__.py
@@ -863,6 +863,12 @@ def write_arrays(
         assert len(dtype) is len(cinfos)
 
         if index is None and isinstance(data_, dict) and "$timestamp" in data_:
+            # Create shallow copy of `data_` so that we don't modify the reference, i.e.
+            # delete keys.
+            #
+            # This ensures that the user can call the same function multiple times without
+            # side-effects.
+            data_ = data_.copy()
             index_ = data_.pop("$timestamp")
             assert "$timestamp" not in data_
         elif index is not None:
diff --git a/scripts/teamcity/20.test.sh b/scripts/teamcity/20.test.sh
index a3b052f2..c3d5d2aa 100644
--- a/scripts/teamcity/20.test.sh
+++ b/scripts/teamcity/20.test.sh
@@ -1,4 +1,4 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 SCRIPT_DIR="$(cd "$(dirname -- "${BASH_SOURCE[0]}")" >/dev/null && pwd)"
 
diff --git a/tests/test_numpy.py b/tests/test_numpy.py
index c3c2f761..86dda992 100644
--- a/tests/test_numpy.py
+++ b/tests/test_numpy.py
@@ -141,6 +141,60 @@ def test_arrays_read_write_data_as_dict(array_with_index_and_table, qdbd_connect
     assert_indexed_arrays_equal((index, data), res)
 
 
+@conftest.override_cdtypes("native")
+def test_provide_index_as_dict(array_with_index_and_table, qdbd_connection):
+    """
+    For convenience, we allow the `$timestamp` index also to provided as a dict
+    key.
+    """
+    (ctype, dtype, data, index, table) = array_with_index_and_table
+
+    col = table.column_id_by_index(0)
+    dict_ = {"$timestamp": index, col: data}
+
+    qdbnp.write_arrays(
+        dict_,
+        qdbd_connection,
+        table,
+        dtype=dtype,
+        infer_types=False,
+        truncate=True,
+    )
+
+    res = qdbnp.read_array(table, col)
+
+    assert_indexed_arrays_equal((index, data), res)
+
+
+@conftest.override_cdtypes("native")
+def test_provide_index_as_dict_has_no_side_effects_sc16279(
+    array_with_index_and_table, qdbd_connection
+):
+    """
+    In earlier versions of the API, we `pop`'ed the $timestamp from the provided dict without making a
+    shallow copy of the dict. This would cause re-invocations of the same function (e.g. in case of an
+    error) to not work, as the original dict had been modified.
+
+    The test below has been confirmed to trigger the original bug described in QDB-16279, and was fixed
+    afterwards.
+    """
+    (ctype, dtype, data, index, table) = array_with_index_and_table
+
+    col = table.column_id_by_index(0)
+
+    dict_ = {"$timestamp": index, col: data}
+    qdbnp.write_arrays(
+        dict_,
+        qdbd_connection,
+        table,
+        dtype=dtype,
+        infer_types=False,
+        truncate=True,
+    )
+
+    assert "$timestamp" in dict_
+
+
 ######
 #
 # Arrays tests