diff --git a/lib/tfw/fsm_base.py b/lib/tfw/fsm_base.py
index d6a586c..fc1300f 100644
--- a/lib/tfw/fsm_base.py
+++ b/lib/tfw/fsm_base.py
@@ -1,11 +1,14 @@
+from typing import List
+
 from transitions import Machine
 
 
 class FSMBase:
     states, transitions = [], []
 
-    def __init__(self, initial: str = None):
+    def __init__(self, initial: str = None, accepted_states: List[str] = None):
         self.message_handlers = []
+        self.accepted_states = accepted_states or [self.states[-1]]
         self.machine = Machine(model=self,
                                states=self.states,
                                transitions=self.transitions,
@@ -24,3 +27,6 @@ class FSMBase:
 
     def unsubscribe_message_handler(self, msghandler):
         self.message_handlers.remove(msghandler)
+
+    def is_solved(self):
+        return self.state in self.accepted_states
diff --git a/src/app/app.py b/src/app/app.py
index 383fd9a..70d3c65 100644
--- a/src/app/app.py
+++ b/src/app/app.py
@@ -20,8 +20,8 @@ def zmq_callback(stream, msg_parts):
         stream.send_multipart(serialize_all(key, 'OK'))
     if key == 'solution_check':
         stream.send_multipart(serialize_all(key, {
-            'solved': True,
-            'message': 'solved'
+            'solved': fsm.is_solved(),
+            'message': 'solved' if fsm.is_solved() else 'not solved'
         }))