diff --git a/processor.go b/processor.go
index eacefb7..8d2c0f1 100644
--- a/processor.go
+++ b/processor.go
@@ -93,16 +93,6 @@ func (p *Processor[AC, OC, JC]) init() error {
 		return nil
 	}
 
-	// validate the states
-	for _, s := range p.states {
-		if !s.Terminal && s.Exec == nil {
-			return fmt.Errorf("State %s is non-terminal but has no Exec function", s.TriggerState)
-		}
-		if !s.Terminal && p.ValidateExitStates && len(s.ExitStates) == 0 {
-			return fmt.Errorf("ValidateExitStates: invalid State machine, state %s is non-terminal but has no ExitStates", s.TriggerState)
-		}
-	}
-
 	if p.serializer == nil {
 		p.serializer = &NilSerializer[OC, JC]{}
 	}
@@ -120,6 +110,26 @@ func (p *Processor[AC, OC, JC]) init() error {
 		p.stateNames = append(p.stateNames, k)
 	}
 
+	// validate the states
+	for _, s := range p.states {
+		if !s.Terminal && s.Exec == nil {
+			return fmt.Errorf("State %s is non-terminal but has no Exec function", s.TriggerState)
+		}
+		if p.ValidateExitStates {
+			if s.Terminal {
+				continue
+			}
+			if len(s.ExitStates) == 0 {
+				return fmt.Errorf("ValidateExitStates: invalid State machine, state %s is non-terminal but has no ExitStates", s.TriggerState)
+			}
+			for _, exit := range s.ExitStates {
+				if _, ok := p.stateMap[exit]; !ok {
+					return fmt.Errorf("invalid exit state [%s] for state %s", exit, s.TriggerState)
+				}
+			}
+		}
+	}
+
 	// For each state, we need a channel of jobs
 	p.stateChan = map[string]chan Job[JC]{}
 
diff --git a/processor_test.go b/processor_test.go
index b997147..a52d3e1 100644
--- a/processor_test.go
+++ b/processor_test.go
@@ -741,6 +741,10 @@ func TestProcessor_NonTerminal_NoExitFunction(t *testing.T) {
 	require.ErrorContains(t, err, fmt.Sprintf("State %s is non-terminal but has no Exec function", TRIGGER_STATE_NEW))
 }
 
+func TestProcessor_ValidExitStates_ContainingSelf_CantBeOnlyState(t *testing.T) {
+	t.Fatal("NYI")
+}
+
 func TestProcessor_ValidateExitStates_InvalidExit(t *testing.T) {
 	t.Parallel()
 	uknownState := "UNKNOWN_EXIT_STATE"
@@ -751,11 +755,7 @@ func TestProcessor_ValidateExitStates_InvalidExit(t *testing.T) {
 				return jc, uknownState, nil, nil
 			},
 			Terminal:   false,
-			ExitStates: []string{TRIGGER_STATE_NEW},
-		},
-		{
-			TriggerState: uknownState,
-			Terminal:     true,
+			ExitStates: []string{uknownState},
 		},
 	}
 	p := NewProcessor[MyAppContext, MyOverallContext, MyJobContext](MyAppContext{}, states, nil, nil)