diff --git a/src/Groups.jl b/src/Groups.jl
index 3c5f3a1..dd29ce4 100644
--- a/src/Groups.jl
+++ b/src/Groups.jl
@@ -412,7 +412,7 @@ end
 #
 ###############################################################################
 
-function generate_balls(S::Vector{T}, Id::T=parent(first(S))(); radius=2, op=*) where T<:GWord
+function generate_balls(S::Vector{T}, Id::T=parent(first(S))(); radius=2, op=*) where T<:GroupElem
     sizes = Int[]
     B = [Id]
     for i in 1:radius