diff --git a/src/dfa.jl b/src/dfa.jl
index 90650508..929266eb 100644
--- a/src/dfa.jl
+++ b/src/dfa.jl
@@ -37,7 +37,7 @@ function validate(dfa::DFA)
     end
 end
 
-function nfa2dfa(nfa::NFA, unambiguous::Bool=false)
+function nfa2dfa(nfa::NFA, unambiguous::Bool=true)
     newnodes = Dict{Set{NFANode},DFANode}()
     new(S) = get!(newnodes, S, DFANode(nfa.final ∈ S, S))
     isvisited(S) = haskey(newnodes, S)
diff --git a/src/machine.jl b/src/machine.jl
index 805266f2..b36b6bd8 100644
--- a/src/machine.jl
+++ b/src/machine.jl
@@ -51,7 +51,7 @@ machine let
 end
 ```
 """
-function compile(re::RegExp.RE; optimize::Bool=true, unambiguous::Bool=false)
+function compile(re::RegExp.RE; optimize::Bool=true, unambiguous::Bool=true)
     dfa = nfa2dfa(remove_dead_nodes(re2nfa(re)), unambiguous)
     if optimize
         dfa = remove_dead_nodes(reduce_nodes(dfa))