diff --git a/PyTeX/build/build/builder.py b/PyTeX/build/build/builder.py
index 29098fb..3d7f1a5 100644
--- a/PyTeX/build/build/builder.py
+++ b/PyTeX/build/build/builder.py
@@ -159,13 +159,20 @@ class PyTeXBuilder:
             files = self.source_root.glob('*')
         for file in files:
             if self.is_supported_file(file.name):
+                config = self.pytex_config.sub_config(
+                    file.name.split('.', 1)[0]
+                )
+                config.merge_with(
+                    self.pytex_config.default_formatting_config,
+                    strict=False
+                )
                 self._pytex_files.append(
                     PyTeXSourceFile(
                         relative_path=RelativePath(
                             self.source_root,
                             file
                         ),
-                        default_config=self.pytex_config.default_formatting_config,
+                        default_config=config,
                         git_version_info=self._git_version_info,
                         target=self._build_target_type.to_target()
                     )
diff --git a/PyTeX/build/build/pytex_config.py b/PyTeX/build/build/pytex_config.py
index 45f4a77..d7a9aab 100644
--- a/PyTeX/build/build/pytex_config.py
+++ b/PyTeX/build/build/pytex_config.py
@@ -96,3 +96,17 @@ class PyTeXConfig(Config):
             return FormattingConfig()
         else:
             return self._default_formatting_config
+
+    @property
+    def sub_configs(self) -> Dict:
+        if self._configs is None:
+            return {}
+        else:
+            return self._configs
+
+    def sub_config(self, name: str) -> FormattingConfig:
+        if name in self.sub_configs.keys():
+            return FormattingConfig.from_json(self.sub_configs[name])
+        else:
+            return FormattingConfig()
+
diff --git a/PyTeX/format/config.py b/PyTeX/format/config.py
index 5965dd5..73de7ca 100644
--- a/PyTeX/format/config.py
+++ b/PyTeX/format/config.py
@@ -58,7 +58,8 @@ def clean_dict(dictionary: Dict) -> Optional[Dict]:
 class Config:
     def merge_with(self, other: Config, strict: bool = False):
         """
-        Merges the other config into this one
+        Merges the other config into this one.
+        In conflicts, the called-on instance takes effect
         :param other:
         :param strict: whether conflicting options are allowed or not
         :return: self
diff --git a/main.py b/main.py
index be32c32..7ae2437 100644
--- a/main.py
+++ b/main.py
@@ -25,7 +25,7 @@ builder = PyTeXBuilder(conf_path)
 
 builder.build_tex_sources()
 
-builder.build_tex_files()
+# builder.build_tex_files()
 
 
 pass