diff --git a/speasy/core/codecs/bundled_codecs/istp_cdf.py b/speasy/core/codecs/bundled_codecs/istp_cdf.py
index 8450d7af..7c12a6d3 100644
--- a/speasy/core/codecs/bundled_codecs/istp_cdf.py
+++ b/speasy/core/codecs/bundled_codecs/istp_cdf.py
@@ -16,7 +16,7 @@
 from speasy.products import SpeasyVariable, VariableAxis, VariableTimeAxis, DataContainer
 
 log = logging.getLogger(__name__)
-_PTR_rx = re.compile(r".*_PTR_\d+")
+_PTR_rx = re.compile(r".*_PTR(_\d+)?")
 
 
 def _fix_value_type(value):
diff --git a/tests/resources/ge_h0_cpi_00000000_v01.cdf b/tests/resources/ge_h0_cpi_00000000_v01.cdf
new file mode 100644
index 00000000..79bd798d
Binary files /dev/null and b/tests/resources/ge_h0_cpi_00000000_v01.cdf differ
diff --git a/tests/test_codecs.py b/tests/test_codecs.py
index e0a416b3..4ec52899 100644
--- a/tests/test_codecs.py
+++ b/tests/test_codecs.py
@@ -85,3 +85,18 @@ def test_variable_is_loaded(self):
 
     def test_variable_shape(self):
         self.assertEqual(self.v.values.shape, (24, 3))
+
+
+@ddt
+class TestCDFWriterPtrAttributes(unittest.TestCase):
+
+    @data(
+        (f"{__HERE__}/resources/ge_h0_cpi_00000000_v01.cdf", "cdf", "SW_V"),
+    )
+    @unpack
+    def test_read_files(self, filename, codec_id, variable):
+        codec = get_codec(codec_id)
+        self.assertIsNotNone(codec)
+        data = codec.load_variable(variable, file=filename)
+        buffer = codec.save_variables([data])
+        self.assertIsNotNone(buffer)