diff --git a/cftscal/objects.py b/cftscal/objects.py
index c61901e..de758ee 100644
--- a/cftscal/objects.py
+++ b/cftscal/objects.py
@@ -115,7 +115,7 @@ def list_calibrations(self, name):
 
 class CalibrationManager:
 
-    P_NAME = re.compile('^(.*)\((.*)\)$')
+    P_NAME = re.compile(r'^(.*)\((.*)\)$')
 
     def __init__(self, object_class):
         self.loaders = []