diff --git a/slpkg/upgrade.py b/slpkg/upgrade.py
index 9540037c..e0f105b7 100644
--- a/slpkg/upgrade.py
+++ b/slpkg/upgrade.py
@@ -44,8 +44,8 @@ class Upgrade(Configs):
 
             for name, package in installed.items():
                 tag: str = self.utils.split_package(package)['tag']
-                if not tag:
-                    if extra_repo.get(name):
+                if not tag:  # Add only slackware original packages that have not tag.
+                    if extra_repo.get(name):  # Avoid installed packages from extra repository.
                         extra_package: str = extra_repo[name]['package']
                         if extra_package[:-4] != package:
                             self.installed_packages.append(Path(package))