diff --git a/package_linter.py b/package_linter.py
index e34cdbf..1cd989f 100755
--- a/package_linter.py
+++ b/package_linter.py
@@ -606,7 +606,7 @@ class Script():
         if self.name == "install":
             if self.contains("/etc/apt/sources.list") \
             or (os.path.exists(self.app_path + "/scripts/_common.sh") and "/etc/apt/sources.list" in open(self.app_path+"/scripts/_common.sh").read()):
-                print_warning(
+                print_error(
                     "[YEP-3.7] Manually messing with apt's sources.lists is strongly discouraged "
                     "and should be avoided. Please consider alternatives like using a .deb directly "
                     "or using experimental helpers (c.f. "