diff --git a/CHANGELOG.md b/CHANGELOG.md
index 810d53b..8a67519 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 ### Fixed
 
 - Support `|` and `|=` operator for tables, and support `+` and `+=` operator for arrays. ([#331](https://github.com/sdispater/tomlkit/issues/331))
+- Fix an index error when setting dotted keys in a table. ([#332](https://github.com/sdispater/tomlkit/issues/332))
 
 ## [0.12.3] - 2023-11-15
 
diff --git a/tomlkit/container.py b/tomlkit/container.py
index 9251a98..78f0764 100644
--- a/tomlkit/container.py
+++ b/tomlkit/container.py
@@ -227,9 +227,9 @@ def append(
                     if item.is_super_table():
                         # We need to merge both super tables
                         if (
-                            self._table_keys[-1] != current_body_element[0]
-                            or key.is_dotted()
+                            key.is_dotted()
                             or current_body_element[0].is_dotted()
+                            or self._table_keys[-1] != current_body_element[0]
                         ):
                             if key.is_dotted() and not self._parsed:
                                 idx = self._get_last_index_before_table()