diff --git a/src/@dseries/subsref.m b/src/@dseries/subsref.m
index a6a65f242cd2f6eb0f94d871a2a3d20c172ebd6d..b4809b890a536feef26738c14d08cad3c08c314a 100644
--- a/src/@dseries/subsref.m
+++ b/src/@dseries/subsref.m
@@ -184,7 +184,7 @@ switch S(1).type
         else
             error('dseries::subsref: dseries object is not empty!')
         end
-    elseif isscalar(S(1).subs{1}) && isnumeric(S(1).subs{1}) && isint(S(1).subs{1})
+    elseif isscalar(S(1).subs{1}) && isint(S(1).subs{1})
         % Input is also interpreted as a backward/forward operator
         if S(1).subs{1}>0
             r = feval('lead', o, S(1).subs{1});