diff --git a/errors.go b/errors.go
index f26db07..f50ea32 100644
--- a/errors.go
+++ b/errors.go
@@ -3,8 +3,8 @@ package copier
 import "errors"
 
 var (
-	ErrInvalidCopyDestination        = errors.New("copy destination is invalid")
-	ErrInvalidCopyFrom               = errors.New("copy from is invalid")
+	ErrInvalidCopyDestination        = errors.New("copy destination must be non-nil and addressable")
+	ErrInvalidCopyFrom               = errors.New("copy from must be non-nil and addressable")
 	ErrMapKeyNotMatch                = errors.New("map's key type doesn't match")
 	ErrNotSupported                  = errors.New("not supported")
 	ErrFieldNameTagStartNotUpperCase = errors.New("copier field name tag must be start upper case")