diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6df2d6c3da..6327789eeb 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -9,6 +9,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Fixed
 
+- Fixed `Integer` validator missing failure description when not a number https://github.com/Textualize/textual/issues/4413
 - Fixed a crash in `DataTable` if you clicked a link in the border https://github.com/Textualize/textual/issues/4410
 
 ### Added
diff --git a/src/textual/validation.py b/src/textual/validation.py
index bc490829cf..4128c360d2 100644
--- a/src/textual/validation.py
+++ b/src/textual/validation.py
@@ -363,7 +363,7 @@ def describe_failure(self, failure: Failure) -> str | None:
         Returns:
             A string description of the failure.
         """
-        if isinstance(failure, Integer.NotAnInteger):
+        if isinstance(failure, (Integer.NotANumber, Integer.NotAnInteger)):
             return "Must be a valid integer."
         elif isinstance(failure, Integer.NotInRange):
             if self.minimum is None and self.maximum is not None:
diff --git a/tests/test_validation.py b/tests/test_validation.py
index 7fccddfb97..c72a64472e 100644
--- a/tests/test_validation.py
+++ b/tests/test_validation.py
@@ -214,3 +214,11 @@ def test_Function_validate(function, failure_description, is_valid):
     assert result.is_valid is is_valid
     if result.failure_descriptions:
         assert result.failure_descriptions[0] == failure_description
+
+
+def test_Integer_failure_description_when_NotANumber():
+    """Regression test for https://github.com/Textualize/textual/issues/4413"""
+    validator = Integer()
+    result = validator.validate("x")
+    assert result.is_valid is False
+    assert result.failure_descriptions[0] == "Must be a valid integer."