diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 71f246f..16d787c 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -4,6 +4,12 @@ Changelog
 Beta Releases
 -------------
 
+1.2.1
+~~~~~
+
+    - Bugfix to ensure ``exclude`` path processing in ``GenomeGroup.add_folder`` always uses full
+      resolved paths for files.
+
 1.2.0
 ~~~~~
 
diff --git a/mutatest/__init__.py b/mutatest/__init__.py
index b417ac9..0a72ce0 100644
--- a/mutatest/__init__.py
+++ b/mutatest/__init__.py
@@ -1,6 +1,6 @@
 """Mutation initialization.
 """
-__version__ = "1.2.0"
+__version__ = "1.2.1"
 
 __title__ = "mutatest"
 __description__ = "Python mutation testing: test your tests!"
diff --git a/mutatest/api.py b/mutatest/api.py
index c91170a..8aa2b19 100644
--- a/mutatest/api.py
+++ b/mutatest/api.py
@@ -495,7 +495,7 @@ def add_folder(
             TypeError: if ``source_folder`` is not a folder.
         """
         source_folder = Path(source_folder)
-        exclude_files = [Path(e) for e in exclude_files] if exclude_files else set()
+        exclude_files = [Path(e).resolve() for e in exclude_files] if exclude_files else set()
 
         if not source_folder.is_dir():
             raise TypeError(f"{source_folder} is not a directory.")