diff --git a/src/doc8/checks.py b/src/doc8/checks.py
index 4e9ecd0..67c073d 100644
--- a/src/doc8/checks.py
+++ b/src/doc8/checks.py
@@ -118,6 +118,9 @@ class CheckValidity(ContentCheck):
             r'^Error in \"code-block\" directive\:\nunknown option: "substitutions".',
             re.MULTILINE,
         ),
+        re.compile(
+            r'^PEP number must be a number from 0 to 9999; "\d{1,4}#[^"]*" is invalid.'
+        ),
     ]
 
     def __init__(self, cfg):