diff --git a/ptulsconv/pdf/__init__.py b/ptulsconv/pdf/__init__.py
index d9ca587..0203c1f 100644
--- a/ptulsconv/pdf/__init__.py
+++ b/ptulsconv/pdf/__init__.py
@@ -99,6 +99,8 @@ def make_doc_template(page_size, filename, document_title,
 
 
 def time_format(mins, zero_str="-"):
+    if mins is None:
+        return zero_str
     if mins == 0. and zero_str is not None:
         return zero_str
     elif mins < 60.:
diff --git a/tests/functional/test_pdf_export.py b/tests/functional/test_pdf_export.py
index 5559473..c7947f5 100644
--- a/tests/functional/test_pdf_export.py
+++ b/tests/functional/test_pdf_export.py
@@ -14,15 +14,15 @@ class TestBroadcastTimecode(unittest.TestCase):
         Setp through every text file in export_cases and make sure it can 
         be converted into PDF docs without throwing an error
         """
-        # for path in glob.glob(os.path.dirname(__file__) + "/../export_cases/*.txt"):
-        #     tempdir = tempfile.TemporaryDirectory()
-        #     os.chdir(tempdir.name)
-        #     try:
-        #         commands.convert(path, major_mode='doc')
-        #     except:
-        #         assert False, "Error processing file %s" % path
-        #     finally:
-        #         tempdir.cleanup()
+        for path in glob.glob(os.path.dirname(__file__) + "/../export_cases/Robin Hood Spotting.txt"):
+            tempdir = tempfile.TemporaryDirectory()
+            os.chdir(tempdir.name)
+            try:
+                commands.convert(path, major_mode='doc')
+            except:
+                assert False, "Error processing file %s" % path
+            finally:
+                tempdir.cleanup()