diff --git a/chain/bank.go b/chain/bank.go
index adad146..c418c06 100644
--- a/chain/bank.go
+++ b/chain/bank.go
@@ -26,9 +26,9 @@ func NewBank(config string, units *unit.Bank) *Bank {
 	}
 }
 
-func (b *Bank) Chain(name string) *Chain {
-	c, _ := b.chains[name]
-	return c
+func (b *Bank) Chain(name string) (c *Chain, ok bool) {
+	c, ok = b.chains[name]
+	return
 }
 
 func (b *Bank) Reload() {
@@ -77,7 +77,7 @@ func (b *Bank) parse(conf interface{}) *Chain {
 				}
 			case reflect.String:
 				name := link.(string)
-				if caller := b.units.Unit(name); caller != nil {
+				if caller, ok := b.units.Unit(name); ok {
 					c.Links = append(c.Links, caller)
 				} else {
 					fmt.Println("Unknown unit:", name)
diff --git a/unit/bank.go b/unit/bank.go
index 20d1e5a..76eafd8 100644
--- a/unit/bank.go
+++ b/unit/bank.go
@@ -22,16 +22,16 @@ func NewBank(config string) *Bank {
 	}
 }
 
-func (b *Bank) Unit(name string) Caller {
+func (b *Bank) Unit(name string) (c Caller, ok bool) {
 	if u, ok := b.units[name]; ok {
 		// Check for unit implementation and create a unit if there is none
 		if imp := impl.New(u.Name, u.Impl); imp != nil {
-			return imp
+			return imp, true
 		} else {
-			return u
+			return u, true
 		}
 	} else {
-		return nil
+		return nil, false
 	}
 }