diff --git a/tests/LexerRules/OrderedListRuleTest.php b/tests/LexerRules/OrderedListRuleTest.php
index a396c3c..be6069a 100644
--- a/tests/LexerRules/OrderedListRuleTest.php
+++ b/tests/LexerRules/OrderedListRuleTest.php
@@ -45,6 +45,14 @@ public function test_numeric_text_without_marker_is_not_an_ordered_list(): void
         $this->assertEquals(new TextToken('2026 is year'), $tokens[0]);
     }
 
+    #[Test]
+    public function test_ordered_list_marker_requires_whitespace_after_period(): void
+    {
+        $tokens = new Lexer([new OrderedListRule(), new TextRule()])->lex('1.not list');
+
+        $this->assertEquals(new TextToken('1.not list'), $tokens[0]);
+    }
+
     #[Test]
     public function test_lex_nested(): void
     {
diff --git a/tests/TokenCollectionTest.php b/tests/TokenCollectionTest.php
index 49a0cc7..38a6dab 100644
--- a/tests/TokenCollectionTest.php
+++ b/tests/TokenCollectionTest.php
@@ -19,4 +19,17 @@ public function test_array_access_append_uses_next_numeric_index(): void
 
         $this->assertSame($token, $collection[0]);
     }
+
+    #[Test]
+    public function test_array_access_can_set_explicit_zero_offset_after_append(): void
+    {
+        $collection = new TokenCollection();
+        $original = new TextToken('x');
+        $replacement = new TextToken('y');
+
+        $collection[] = $original;
+        $collection[0] = $replacement;
+
+        $this->assertSame($replacement, $collection[0]);
+    }
 }