diff --git a/nd2reader/label_map.py b/nd2reader/label_map.py
index dcd2e9c..2a2eb91 100644
--- a/nd2reader/label_map.py
+++ b/nd2reader/label_map.py
@@ -72,7 +72,7 @@ def get_image_data_location(self, index):
 
         """
         if not self._image_data:
-            regex = re.compile(six.b("""ImageDataSeq\|(\d+)!"""))
+            regex = re.compile(six.b(r"ImageDataSeq\|(\d+)!"))
             for match in regex.finditer(self._data):
                 if match:
                     location = self._parse_data_location(match.end())