diff --git a/staplelib/commands.py b/staplelib/commands.py
index d37bfa7..6082d28 100644
--- a/staplelib/commands.py
+++ b/staplelib/commands.py
@@ -296,7 +296,8 @@ def pdf_page_enumeration(pdf):
         if len(pagelabels_nums_list) > 0 and i >= pagelabels_nums_list[0]:
             pagelabels_nums_list.pop(0)  # discard index
             pnle = pagelabels_nums_list.pop(0)
-            style = pnle.get('/S', '/D')
+            # An omitted /S means the label consists only of its prefix.
+            style = pnle.get('/S')
             prefix = pnle.get('/P', '')
             next_pageno = pnle.get('/St', 1)
         pageno_str = ''
@@ -310,7 +311,7 @@ def pdf_page_enumeration(pdf):
             pageno_str = int_to_roman(next_pageno)
         elif style == '/r':
             pageno_str = int_to_roman(next_pageno).lower()
-        else:
+        elif style is not None:
             raise CommandError("Malformded PDF: unkown page numbering style " + style)
         labels.append(prefix + pageno_str)
         next_pageno += 1
diff --git a/tests/test_oss_regression_62.py b/tests/test_oss_regression_62.py
new file mode 100644
index 0000000..a1dd2bc
--- /dev/null
+++ b/tests/test_oss_regression_62.py
@@ -0,0 +1,81 @@
+"""Regression coverage for prefix-only PDF page labels (issue #62)."""
+
+import pytest
+from PyPDF2 import PdfFileWriter
+from PyPDF2.generic import (
+    ArrayObject,
+    DictionaryObject,
+    NameObject,
+    NumberObject,
+    createStringObject,
+)
+
+from staplelib import main
+
+
+@pytest.mark.parametrize(
+    "ranges, expected",
+    [
+        (
+            [(0, {"/P": "1"}), (1, {"/P": "2"}), (2, {"/P": "3"})],
+            ["1", "2", "3"],
+        ),
+        (
+            [(0, {"/P": "i"}), (1, {"/P": "ii"}),
+             (2, {"/P": "1"}), (3, {"/P": "2"})],
+            ["i", "ii", "1", "2"],
+        ),
+        ([(0, {"/P": "Cover", "/St": 12})], ["Cover", "Cover", "Cover"]),
+        ([(0, {})], ["", ""]),
+        ([(0, {"/S": "/D", "/P": "A-", "/St": 9})], ["A-9", "A-10"]),
+        (
+            [(0, {"/S": "/D", "/St": 7}),
+             (1, {"/S": "/A", "/St": 27}),
+             (2, {"/S": "/a", "/St": 2}),
+             (3, {"/S": "/R", "/St": 4}),
+             (4, {"/S": "/r", "/St": 6})],
+            ["7", "AA", "b", "IV", "vi"],
+        ),
+        (None, ["1", "2", "3"]),
+    ],
+    ids=[
+        "numeric-prefixes",
+        "roman-and-numeric-prefixes",
+        "prefix-only-range",
+        "empty-prefix",
+        "decimal-prefix-and-start",
+        "explicit-numbering-styles",
+        "no-page-labels",
+    ],
+)
+def test_list_logical_page_labels(tmp_path, capsys, ranges, expected):
+    writer = PdfFileWriter()
+    for _ in expected:
+        writer.addBlankPage(72, 72)
+
+    if ranges is not None:
+        nums = ArrayObject()
+        for index, values in ranges:
+            label = DictionaryObject()
+            for key, value in values.items():
+                if key == "/S":
+                    label[NameObject(key)] = NameObject(value)
+                elif key == "/St":
+                    label[NameObject(key)] = NumberObject(value)
+                else:
+                    label[NameObject(key)] = createStringObject(value)
+            nums.extend([NumberObject(index), label])
+        writer._root_object[NameObject("/PageLabels")] = DictionaryObject(
+            {NameObject("/Nums"): nums}
+        )
+
+    path = tmp_path / "labels.pdf"
+    with path.open("wb") as stream:
+        writer.write(stream)
+
+    main(["list-logical", str(path)])
+
+    assert capsys.readouterr().out == "".join(
+        "{}\t{}\n".format(label, index)
+        for index, label in enumerate(expected, 1)
+    )