diff --git a/classes/state_machine/state_machine.gd b/classes/state_machine/state_machine.gd
index d773d4c..e535dac 100644
--- a/classes/state_machine/state_machine.gd
+++ b/classes/state_machine/state_machine.gd
@@ -10,6 +10,7 @@ class_name StateMachine extends Node
 
 
 func _ready() -> void:
+	assert(state != null, "initial state is null")
 	for state_node: State in find_children("*", "State"):
 		# fixes duplicate connections (not sure why)
 		if not state_node.finished.is_connected(_transition_to_next_state):