diff --git a/QueryKit.IntegrationTests/Tests/PropertyResolverTests.cs b/QueryKit.IntegrationTests/Tests/PropertyResolverTests.cs
index 9c3487c..0483422 100644
--- a/QueryKit.IntegrationTests/Tests/PropertyResolverTests.cs
+++ b/QueryKit.IntegrationTests/Tests/PropertyResolverTests.cs
@@ -533,6 +533,34 @@ public async Task prevented_property_clause_by_its_query_name_under_or_does_not_
         people.Should().BeEmpty();
     }
 
+    [Fact]
+    public async Task unknown_property_in_arithmetic_removes_the_clause_when_unknown_properties_are_allowed()
+    {
+        // Arrange
+        var testingServiceScope = new TestingServiceScope();
+        var title = new Faker().Lorem.Sentence();
+        var fakePerson = new FakeTestingPersonBuilder()
+            .WithTitle(title)
+            .WithAge(30)
+            .Build();
+        await testingServiceScope.InsertAsync(fakePerson);
+
+        var input = $"""Title == "{title}" && ((Nope + 1) > 3 || Age > 100)""";
+        var config = new QueryKitConfiguration(config =>
+        {
+            config.IgnoredClauseBehavior = IgnoredClauseBehavior.Remove;
+            config.AllowUnknownProperties = true;
+        });
+
+        // Act
+        var people = await testingServiceScope.DbContext().People
+            .ApplyQueryKitFilter(input, config)
+            .ToListAsync();
+
+        // Assert
+        people.Should().BeEmpty();
+    }
+
     [Theory]
     [InlineData("first-name")]
     [InlineData("_first")]
diff --git a/QueryKit.UnitTests/PropertyResolverTests.cs b/QueryKit.UnitTests/PropertyResolverTests.cs
index 4707579..3305c06 100644
--- a/QueryKit.UnitTests/PropertyResolverTests.cs
+++ b/QueryKit.UnitTests/PropertyResolverTests.cs
@@ -967,7 +967,7 @@ public void quoted_value_with_a_dot_on_the_right_side_is_a_value(string input, s
     }
 
     [Fact]
-    public void unknown_property_in_arithmetic_throws_when_unknown_properties_are_allowed()
+    public void unknown_property_in_arithmetic_removes_the_clause_when_unknown_properties_are_allowed()
     {
         var input = """(Nope + 1) > 3 || Age > 100""";
         var config = new QueryKitConfiguration(config =>
@@ -976,14 +976,13 @@ public void unknown_property_in_arithmetic_throws_when_unknown_properties_are_al
             config.AllowUnknownProperties = true;
         });
 
-        var act = () => FilterParser.ParseFilter<TestingPerson>(input, config);
+        var filterExpression = FilterParser.ParseFilter<TestingPerson>(input, config);
 
-        act.Should().Throw<ArgumentException>()
-            .WithMessage("Property 'Nope' not found on type 'TestingPerson'");
+        filterExpression.ToDisplayString().Should().Be("x => (x.Age > 100)");
     }
 
     [Fact]
-    public void unknown_property_on_the_right_side_of_arithmetic_throws_when_unknown_properties_are_allowed()
+    public void unknown_property_on_the_right_side_of_arithmetic_removes_the_clause_when_unknown_properties_are_allowed()
     {
         var input = """(Age + 0) > Nope || Title == "a" """;
         var config = new QueryKitConfiguration(config =>
@@ -992,21 +991,20 @@ public void unknown_property_on_the_right_side_of_arithmetic_throws_when_unknown
             config.AllowUnknownProperties = true;
         });
 
-        var act = () => FilterParser.ParseFilter<TestingPerson>(input, config);
+        var filterExpression = FilterParser.ParseFilter<TestingPerson>(input, config);
 
-        act.Should().Throw<ArgumentException>()
-            .WithMessage("Property 'Nope' not found on type 'TestingPerson'");
+        filterExpression.ToDisplayString().Should().Be("""x => (x.Title == "a")""");
     }
 
     [Fact]
-    public void unknown_property_in_arithmetic_throws_an_argument_exception()
+    public void unknown_property_in_arithmetic_is_not_recognized()
     {
         var input = """(Nope + 1) > 3""";
 
         var act = () => FilterParser.ParseFilter<TestingPerson>(input);
 
-        act.Should().Throw<ArgumentException>()
-            .WithMessage("Property 'Nope' not found on type 'TestingPerson'");
+        act.Should().Throw<UnknownFilterPropertyException>()
+            .WithMessage("The filter property 'Nope' was not recognized.");
     }
 
     [Theory]
diff --git a/QueryKit/FilterParser.cs b/QueryKit/FilterParser.cs
index 275b5c9..551d5ff 100644
--- a/QueryKit/FilterParser.cs
+++ b/QueryKit/FilterParser.cs
@@ -896,16 +896,22 @@ private static Parser<Expression> ArithmeticComparisonExprParser<T>(ParameterExp
     }
     
     // Resolves each property in an arithmetic expression to its member path.
-    // Returns null when a property cannot be filtered, because then the parser removes the clause.
+    // Returns null when a property cannot be filtered or is an allowed unknown property, because then the parser removes the clause.
     private static ArithmeticExpression? ResolveArithmeticProperties(ArithmeticExpression expr, Type entityType, IQueryKitConfiguration? config)
     {
         switch (expr)
         {
             case PropertyArithmeticExpression property:
                 var reference = PropertyResolver.Resolve(entityType, property.PropertyPath, config);
+                // Arithmetic supports only members, so a derived property or a custom operation is unknown here
                 if (reference.Kind != PropertyReferenceKind.Member)
                 {
-                    return property;
+                    if (config?.AllowUnknownProperties == true)
+                    {
+                        return null;
+                    }
+
+                    throw new UnknownFilterPropertyException(reference.UnknownSegment ?? property.PropertyPath);
                 }
 
                 return reference.CanFilter ? new PropertyArithmeticExpression(reference.Path) : null;
diff --git a/README.md b/README.md
index 3b5ebad..7299a7f 100644
--- a/README.md
+++ b/README.md
@@ -386,6 +386,7 @@ var input = "((Revenue - Expenses) / Revenue) > 0.1";
 - **Parentheses**: Use parentheses to control calculation order and group expressions
 - **Entity Framework Translation**: All arithmetic expressions are translated to efficient SQL queries
 - **Property-to-Property**: Can mix property references with literal values in the same expression
+- **Unknown Properties**: An unknown property in an arithmetic expression throws `UnknownFilterPropertyException`, like any other filter property. When `AllowUnknownProperties` is `true`, QueryKit ignores the clause. Arithmetic supports only entity members, so a derived property or a custom operation name is unknown here
 
 #### Examples