diff --git a/src/AutGroup.jl b/src/AutGroup.jl
index 539856a..bbdb3cc 100644
--- a/src/AutGroup.jl
+++ b/src/AutGroup.jl
@@ -41,7 +41,7 @@ mutable struct Automorphism{N} <: GWord{AutSymbol}
     savedhash::UInt
     parent::AutGroup{N}
 
-    Automorphism{N}(f::Vector{AutSymbol}) where N = new(f, true)
+    Automorphism{N}(f::Vector{AutSymbol}) where N = new(f, true, zero(UInt))
 
 end