diff --git a/src/@dates/setdiff.m b/src/@dates/setdiff.m
index c72c5ef74d3f9c9a2888b2259c766515a4afecb7..79f689bb15c2fbfba5b593547c07beb6cc125651 100644
--- a/src/@dates/setdiff.m
+++ b/src/@dates/setdiff.m
@@ -49,7 +49,7 @@ if isequal(o.length(),p.length()) && isequal(o, p)
 end
 
 if isoctave && octave_ver_less_than('6')
-    if o.freq==2
+    if o.freq==365
         [~, io] = setdiff(o.time(:,1), p.time(:,1));
         time = o.time(io,:);
     else