diff --git a/builder.hpp b/builder.hpp
index ce8b995..6b0e050 100644
--- a/builder.hpp
+++ b/builder.hpp
@@ -53,7 +53,7 @@ class Builder : DeadSimpleFSM<BuildState, BuildEvent> {
   string read_line(FILE *build_out, bool &done_out);
   FILE *start_command(string &build_cmd);
 
-  void event(BuildEvent ev) override {
+  void event(BuildEvent ev) {
     try {
       if(ev == QUIT) {
         exit(ev);
diff --git a/fsm.hpp b/fsm.hpp
index 82dce66..d0fe917 100644
--- a/fsm.hpp
+++ b/fsm.hpp
@@ -3,9 +3,9 @@
 #include <fmt/core.h>
 
 #ifndef FSM_DEBUG
-#define FSM_STATE(C, S, F, E) case C::S: F(E); break
+#define FSM_STATE(C, S, F, E, ...) case C::S: F(E, ##__VA_ARGS__); break
 #else
-#define FSM_STATE(C, S, F, E) case C::S: fmt::println(">> " #C " " #S ":" #F " event={}, state={}", int(E), int(_state)); F(E); fmt::println("<< " #C " state={}", int(_state)); break
+#define FSM_STATE(C, S, F, E, ...) case C::S: fmt::println(">> " #C " " #S ":" #F " event={}, state={}", int(E), int(_state)); F(E, ##__VA_ARGS__); fmt::println("<< " #C " state={}", int(_state)); break
 #endif
 
 template<typename S, typename E>
@@ -15,7 +15,8 @@ protected:
   S _state = S::START;
 
 public:
-  virtual void event(E event) = 0;
+  template<typename... Types>
+  void event(E event, Types... args);
 
   void state(S next_state) {
     _state = next_state;
diff --git a/game_engine.hpp b/game_engine.hpp
index 035980d..3b517f5 100644
--- a/game_engine.hpp
+++ b/game_engine.hpp
@@ -48,32 +48,15 @@ class GameEngine : DeadSimpleFSM<GameState, GameEvent> {
   int determine_damage(string &type);
   bool is_dead();
 
-  void event(GameEvent ev, string &hit_type) {
-    switch(_state) {
-      case GameState::IN_ROUND:
-        in_round(ev, hit_type);
-        break;
-      default:
-        event(ev);
-    }
-  }
-
-  void event(GameEvent ev, const char *hit_type) {
-    string ht{hit_type};
-    event(ev, ht);
-  }
-
-  void event(GameEvent ev) {
+  void event(GameEvent ev, string hit_type="") {
     switch(_state) {
       FSM_STATE(GameState, START, start, ev);
       FSM_STATE(GameState, IDLE, idle, ev);
       FSM_STATE(GameState, DEAD, dead, ev);
       FSM_STATE(GameState, SUCCESS, success, ev);
       FSM_STATE(GameState, FAILURE, failure, ev);
-      case GameState::IN_ROUND: {
-        string hit_type = "";
+      case GameState::IN_ROUND:
         in_round(ev, hit_type);
-        }
         break;
     }
   }
diff --git a/meson.build b/meson.build
index eba88b8..aa39278 100644
--- a/meson.build
+++ b/meson.build
@@ -39,6 +39,7 @@ executable('escape_turings_tarpit',
 runtests = executable('runtests', [
   'game_engine.cpp',
   'tests/game_engine.cpp',
+  'tests/fsm.cpp',
   ],
   dependencies: dependencies + [catch2])
 
diff --git a/scratchpad/fsmtest.cpp b/scratchpad/fsmtest.cpp
deleted file mode 100644
index 4864330..0000000
--- a/scratchpad/fsmtest.cpp
+++ /dev/null
@@ -1,48 +0,0 @@
-#include <fmt/core.h>
-#include "../fsm.hpp"
-
-using namespace fmt;
-
-enum class MyState {
-  START, RUNNING, END
-};
-
-enum class MyEvent {
-  STARTED, PUSH, QUIT
-};
-
-class MyFSM : DeadSimpleFSM<MyState, MyEvent> {
-public:
-  void event(MyEvent ev) override {
-    switch(_state) {
-      FSM_STATE(MyState, START, start, ev);
-      FSM_STATE(MyState, RUNNING, push, ev);
-      FSM_STATE(MyState, END, quit, ev);
-    }
-  }
-
-  void start(MyEvent ev) {
-    println("<<< START");
-    state(MyState::RUNNING);
-  }
-
-  void push(MyEvent ev) {
-    println("<<< RUN");
-    state(MyState::RUNNING);
-  }
-
-  void quit(MyEvent ev) {
-    println("<<< STOP");
-    state(MyState::END);
-  }
-};
-
-int main() {
-  MyFSM fsm;
-
-  fsm.event(MyEvent::STARTED);
-  fsm.event(MyEvent::PUSH);
-  fsm.event(MyEvent::PUSH);
-  fsm.event(MyEvent::PUSH);
-  fsm.event(MyEvent::QUIT);
-}
diff --git a/scratchpad/meson.build b/scratchpad/meson.build
index 0597ebf..cef6686 100644
--- a/scratchpad/meson.build
+++ b/scratchpad/meson.build
@@ -10,9 +10,6 @@ executable('jsontest', 'jsontest.cpp',
 executable('threadtest', 'threadtest.cpp',
   dependencies: dependencies)
 
-executable('fsmtest', 'fsmtest.cpp',
-  dependencies: dependencies)
-
 executable('badref', 'badref.cpp',
   dependencies: dependencies)
 
diff --git a/tests/fsm.cpp b/tests/fsm.cpp
new file mode 100644
index 0000000..0440098
--- /dev/null
+++ b/tests/fsm.cpp
@@ -0,0 +1,67 @@
+#include <catch2/catch_test_macros.hpp>
+#include <fmt/core.h>
+#include <string>
+#include "../fsm.hpp"
+
+using namespace fmt;
+using std::string;
+
+enum class MyState {
+  START, RUNNING, END
+};
+
+enum class MyEvent {
+  STARTED, PUSH, QUIT
+};
+
+class MyFSM : public DeadSimpleFSM<MyState, MyEvent> {
+public:
+  void event(MyEvent ev, string data="") {
+    switch(_state) {
+      FSM_STATE(MyState, START, START, ev);
+      FSM_STATE(MyState, RUNNING, RUNNING, ev, data);
+      FSM_STATE(MyState, END, END, ev);
+    }
+  }
+
+  void START(MyEvent ev) {
+    println("<<< START");
+    state(MyState::RUNNING);
+  }
+
+  void RUNNING(MyEvent ev, string &data) {
+    if(ev == MyEvent::QUIT) {
+      println("<<< QUITTING {}", data);
+      state(MyState::END);
+    } else {
+      println("<<< RUN: {}", data);
+      state(MyState::RUNNING);
+    }
+  }
+
+  void END(MyEvent ev) {
+    println("<<< STOP");
+    state(MyState::END);
+  }
+};
+
+TEST_CASE("confirm fsm works with optional data", "[utils]") {
+  MyFSM fsm;
+
+  REQUIRE(fsm.in_state(MyState::START));
+
+  fsm.event(MyEvent::STARTED);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::PUSH);
+  REQUIRE(fsm.in_state(MyState::RUNNING));
+
+  fsm.event(MyEvent::QUIT, "DONE!");
+  REQUIRE(fsm.in_state(MyState::END));
+}