diff --git a/types/stdlib/stdlib.go b/types/stdlib/stdlib.go
index dd9f4efad1..acb7863059 100644
--- a/types/stdlib/stdlib.go
+++ b/types/stdlib/stdlib.go
@@ -7,7 +7,8 @@ import (
 	wire "github.com/cosmos/cosmos-sdk/wire"
 )
 
-type ListMapper interface { // Solidity list like structure
+// Solidity list like structure
+type ListMapper interface {
 	Len(sdk.Context) int64
 	Get(sdk.Context, int64, interface{})
 	Set(sdk.Context, int64, interface{})
@@ -90,6 +91,7 @@ func (lm listMapper) Iterate(ctx sdk.Context, ptr interface{}, fn func(sdk.Conte
 	}
 }
 
+// mapper interface for queue
 type QueueMapper interface {
 	Push(sdk.Context, interface{})
 	Peek(sdk.Context, interface{})