diff --git a/PyPDF2/_merger.py b/PyPDF2/_merger.py
index 37955b030..467ef8124 100644
--- a/PyPDF2/_merger.py
+++ b/PyPDF2/_merger.py
@@ -134,6 +134,9 @@ def merge(
         # Create a new PdfReader instance using the stream
         # (either file or BytesIO or StringIO) created above
         reader = PdfReader(stream, strict=self.strict)  # type: ignore[arg-type]
+
+        # Keep track of our input files so we can close them later
+        self.inputs.append((stream, reader, my_file))
         if decryption_key is not None:
             reader._decryption_key = decryption_key
 
@@ -183,9 +186,6 @@ def merge(
         # Slice to insert the pages at the specified position
         self.pages[position:position] = srcpages
 
-        # Keep track of our input files so we can close them later
-        self.inputs.append((stream, reader, my_file))
-
     def _create_stream(
         self, fileobj: Union[StrByteType, PdfReader]
     ) -> Tuple[IOBase, bool, Optional[bytes]]:
diff --git a/tests/test_merger.py b/tests/test_merger.py
index 6bc776b46..e8cb7999f 100644
--- a/tests/test_merger.py
+++ b/tests/test_merger.py
@@ -1,6 +1,8 @@
 import os
 import sys
 
+import pytest
+
 import PyPDF2
 from PyPDF2.generic import Destination
 
@@ -24,6 +26,7 @@ def test_merge():
     merger.append(outline)
     merger.append(pdf_path, pages=PyPDF2.pagerange.PageRange(slice(0, 0)))
     merger.append(pdf_forms)
+    merger.merge(0, pdf_path, import_bookmarks=False)
 
     # Merging an encrypted file
     reader = PyPDF2.PdfReader(pdf_pw)
@@ -61,6 +64,13 @@ def test_merge():
     merger.add_bookmark(
         "The FitBV fit", 0, bookmark, (255, 0, 15), True, True, "/FitBV", 10
     )
+
+    found_bm = merger.find_bookmark("nothing here")
+    assert found_bm is None
+
+    found_bm = merger.find_bookmark("foo")
+    assert found_bm == [9]
+
     merger.add_metadata({"author": "Martin Thoma"})
     merger.add_named_destination("title", 0)
     merger.set_page_layout("/SinglePage")
@@ -92,3 +102,56 @@ def test_merge():
 
     # Clean up
     os.remove(tmp_path)
+
+
+def test_merge_page_exception():
+    merger = PyPDF2.PdfMerger()
+    pdf_path = os.path.join(RESOURCE_ROOT, "crazyones.pdf")
+    with pytest.raises(TypeError) as exc:
+        merger.merge(0, pdf_path, pages="a:b")
+    assert exc.value.args[0] == '"pages" must be a tuple of (start, stop[, step])'
+    merger.close()
+
+
+def test_merge_page_tuple():
+    merger = PyPDF2.PdfMerger()
+    pdf_path = os.path.join(RESOURCE_ROOT, "crazyones.pdf")
+    merger.merge(0, pdf_path, pages=(0, 1))
+    merger.close()
+
+
+def test_merge_write_closed_fh():
+    merger = PyPDF2.PdfMerger()
+    pdf_path = os.path.join(RESOURCE_ROOT, "crazyones.pdf")
+    merger.append(pdf_path)
+
+    err_closed = "close() was called and thus the writer cannot be used anymore"
+
+    merger.close()
+    with pytest.raises(RuntimeError) as exc:
+        merger.write("stream.pdf")
+    assert exc.value.args[0] == err_closed
+
+    with pytest.raises(RuntimeError) as exc:
+        merger.add_metadata({"author": "Martin Thoma"})
+    assert exc.value.args[0] == err_closed
+
+    with pytest.raises(RuntimeError) as exc:
+        merger.set_page_layout("/SinglePage")
+    assert exc.value.args[0] == err_closed
+
+    with pytest.raises(RuntimeError) as exc:
+        merger.set_page_mode("/UseNone")
+    assert exc.value.args[0] == err_closed
+
+    with pytest.raises(RuntimeError) as exc:
+        merger._write_bookmarks()
+    assert exc.value.args[0] == err_closed
+
+    with pytest.raises(RuntimeError) as exc:
+        merger.add_bookmark("A bookmark", 0)
+    assert exc.value.args[0] == err_closed
+
+    with pytest.raises(RuntimeError) as exc:
+        merger._write_dests()
+    assert exc.value.args[0] == err_closed