diff --git a/pypdf/generic/_base.py b/pypdf/generic/_base.py
index a1164c411..3fde174b0 100644
--- a/pypdf/generic/_base.py
+++ b/pypdf/generic/_base.py
@@ -615,7 +615,7 @@ def write_to_stream(
     def renumber(self) -> bytes:
         out = self[0].encode("utf-8")
         if out != b"/":
-            deprecate_no_replacement(f"Incorrect first char in NameObject, should start with '/':({self})","5.0.0")
+            deprecate_no_replacement(f"Incorrect first char in NameObject, should start with '/': ({self})", "6.0.0")
         for c in self[1:]:
             if c > "~":
                 for x in c.encode("utf-8"):