diff --git a/buildstream/_artifactcache/artifactcache.py b/buildstream/_artifactcache/artifactcache.py
index f33b112bc75ac311cb5a88641751b836c37a529c..4aa7ec55594048d55d0120ffccd86b0afc8f0463 100644
--- a/buildstream/_artifactcache/artifactcache.py
+++ b/buildstream/_artifactcache/artifactcache.py
@@ -242,15 +242,6 @@ class ArtifactCache():
         raise ImplError("Cache '{kind}' does not implement commit()"
                         .format(kind=type(self).__name__))
 
-    # can_diff():
-    #
-    # Whether this cache implementation can diff (unfortunately
-    # there's no way to tell if an implementation is going to throw
-    # ImplError without abc).
-    #
-    def can_diff(self):
-        return False
-
     # diff():
     #
     # Return a list of files that have been added or modified between
diff --git a/buildstream/_artifactcache/cascache.py b/buildstream/_artifactcache/cascache.py
index a3fd16af4562fc38be0cc967025db17452019802..4f61edd7d31d458f20e35373080d480fe379d9d4 100644
--- a/buildstream/_artifactcache/cascache.py
+++ b/buildstream/_artifactcache/cascache.py
@@ -113,9 +113,6 @@ class CASCache(ArtifactCache):
         for ref in refs:
             self.set_ref(ref, tree)
 
-    def can_diff(self):
-        return True
-
     def diff(self, element, key_a, key_b, *, subdir=None):
         ref_a = self.get_artifact_fullname(element, key_a)
         ref_b = self.get_artifact_fullname(element, key_b)