diff --git a/store/iavlstore.go b/store/iavlstore.go
index a1a48722c..330358d8d 100644
--- a/store/iavlstore.go
+++ b/store/iavlstore.go
@@ -138,7 +138,6 @@ func (st *iavlStore) Subspace(prefix []byte) Iterator {
 			}
 		}
 	}
-	fmt.Printf("%v \n", end)
 	return st.Iterator(prefix, end)
 }
 
@@ -242,7 +241,6 @@ func newIAVLIterator(tree *iavl.Tree, start, end []byte, ascending bool) *iavlIt
 		quitCh:    make(chan struct{}),
 		initCh:    make(chan struct{}),
 	}
-	fmt.Printf("%v   %v \n", iter.start, iter.end)
 	go iter.iterateRoutine()
 	go iter.initRoutine()
 	return iter
@@ -356,6 +354,9 @@ func (iter *iavlIterator) assertIsValid() {
 //----------------------------------------
 
 func cp(bz []byte) (ret []byte) {
+	if bz == nil {
+		return nil
+	}
 	ret = make([]byte, len(bz))
 	copy(ret, bz)
 	return ret
diff --git a/store/iavlstore_test.go b/store/iavlstore_test.go
index 02b0d58bb..406d26926 100644
--- a/store/iavlstore_test.go
+++ b/store/iavlstore_test.go
@@ -150,6 +150,10 @@ func TestIAVLSubspace(t *testing.T) {
 	iavlStore.Set([]byte{byte(55), byte(255), byte(255), byte(0)}, []byte("test4"))
 	iavlStore.Set([]byte{byte(55), byte(255), byte(255), byte(1)}, []byte("test4"))
 	iavlStore.Set([]byte{byte(55), byte(255), byte(255), byte(255)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(255), byte(255), byte(0)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(255), byte(255), byte(1)}, []byte("test4"))
+	iavlStore.Set([]byte{byte(255), byte(255), byte(255)}, []byte("test4"))
+
 	i := 0
 
 	iter := iavlStore.Subspace([]byte("test"))