diff --git a/cue_to_meta.py b/cue_to_meta.py
index 30317e8..9ed276a 100644
--- a/cue_to_meta.py
+++ b/cue_to_meta.py
@@ -23,16 +23,17 @@
 # TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
 # SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
+import io
 import re
 
 import click
 
 
-def cue_to_meta(cuefile, metafile):
+def cue_to_meta(cuefile: io.StringIO, metafile: io.StringIO) -> None:
     """Convert CUE to META."""
-    title = None
-    performer = None
-    timestamp = None
+    title = ""
+    performer = ""
+    timestamp = ""
 
     for line in cuefile.readlines():
         title_re = re.search(r'^    TITLE "(.*)"$', line)
@@ -44,17 +45,18 @@ def cue_to_meta(cuefile, metafile):
             performer = performer_re[1]
         if index_re:
             time_re = re.search(r"^(..):(..):..$", index_re[1])
-            timestamp = f"00{time_re[1]}{time_re[2]}"
-        if title and performer and timestamp:
+            if time_re:
+                timestamp = f"00{time_re[1]}{time_re[2]}"
+        if title != "" and performer != "" and timestamp != "":
             metafile.write(f"{timestamp}:{performer} - {title}\n")
-            title = None
-            performer = None
-            timestamp = None
+            title = ""
+            performer = ""
+            timestamp = ""
 
 
 @click.command()
 @click.argument("cuefile", type=click.File("r"))
 @click.argument("metafile", type=click.File("w"))
-def cli(cuefile, metafile):
+def cli(cuefile: io.StringIO, metafile: io.StringIO) -> None:
     """Convert CUEFILE to meta format as METAFILE."""
     cue_to_meta(cuefile, metafile)
diff --git a/test_cue_to_meta.py b/test_cue_to_meta.py
index aa94a48..f4df077 100644
--- a/test_cue_to_meta.py
+++ b/test_cue_to_meta.py
@@ -26,7 +26,7 @@ import io
 import cue_to_meta
 
 
-def test_cue_to_meta():
+def test_cue_to_meta() -> None:
     """Test CUE to META conversion."""
     cue_text = """PERFORMER "mcornick"
 TITLE "Luv'n Time International"