diff --git a/sunkit_instruments/response/abstractions.py b/sunkit_instruments/response/abstractions.py
index 99074cc9..41a148d1 100644
--- a/sunkit_instruments/response/abstractions.py
+++ b/sunkit_instruments/response/abstractions.py
@@ -70,7 +70,7 @@ def energy_per_photon(self) -> u.eV / u.photon:
 
     @abc.abstractmethod
     @u.quantity_input
-    def degradation(self, obstime=None): ...
+    def degradation(self, obstime=None) -> u.dimensionless_unscaled: ...
 
     @property
     @abc.abstractmethod