diff --git a/state-machine/state-machine.d.ts b/state-machine/state-machine.d.ts
index efecb2e4c3..3415beb7c8 100644
--- a/state-machine/state-machine.d.ts
+++ b/state-machine/state-machine.d.ts
@@ -11,7 +11,7 @@ interface StateMachineErrorCallback {
 
 interface StateMachineEventDef {
     name: string;
-    from: string;
+    from: any;    // string or string[]
     to: string;
 }
 
@@ -78,4 +78,4 @@ interface StateMachine {
     transition: StateMachineTransition;
 }
 
-declare var StateMachine: StateMachineStatic;
\ No newline at end of file
+declare var StateMachine: StateMachineStatic;