diff --git a/src/automata.cpp b/src/automata.cpp
index 07605d7..b2d1a34 100644
--- a/src/automata.cpp
+++ b/src/automata.cpp
@@ -7,7 +7,7 @@
 namespace lxs {
     std::string toDot(const DFA& d)
     {
-        std::string s = "digraph {\nrankdir=LR\nin [shape=point style=invis]";
+        std::string s = "digraph {\nrankdir=LR\nin [shape=point style=invis]\n";
 
         for (State state = 0; state < d.numStates; state++)
         {
@@ -128,7 +128,7 @@ namespace lxs {
             return rev;
         }
 
-        void markReachable(const DFA& d, State s, std::set<State> reachable) {
+        void markReachable(const DFA& d, State s, std::set<State>& reachable) {
             if (reachable.count(s) > 0)
                 return;
             reachable.insert(s);
@@ -194,7 +194,7 @@ namespace lxs {
         /**
          * Do the actual minimisation, using precomputed distinguishable pairs
          */
-        DFA compress(const DFA& d, std::set<State> reachables, Distinguishables& dist) {
+        DFA compress(const DFA& d, std::set<State>& reachables, Distinguishables& dist) {
             DFA min;
             min.starting = d.starting;
 
@@ -244,9 +244,8 @@ namespace lxs {
             for (State s = 0; s < d.numStates; s++) {
                 if (done.count(newStates[s]) > 0) continue;
                 done.insert(newStates[s]);
-                for (int i = 0; i < 256; i++) {
-                    min.delta[newStates[s]][(char) i] = newStates[d.delta.find(s)->second.find((char) i)->second];
-                }
+                for (const auto& p : d.delta.find(s)->second)
+                    min.delta[newStates[s]][p.first] = newStates[p.second];
             }
 
             return min;