diff --git a/pySEQTarget/SEQoutput.py b/pySEQTarget/SEQoutput.py
index 42a848e..d01a9a7 100644
--- a/pySEQTarget/SEQoutput.py
+++ b/pySEQTarget/SEQoutput.py
@@ -83,7 +83,7 @@ def summary(
             case _:
                 models = self.outcome_models
 
-        return [model.summary() for model in models]
+        return [model.summary() for model in models if model is not None]
 
     def retrieve_data(
         self,
diff --git a/pyproject.toml b/pyproject.toml
index f480e67..830ec6c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -4,7 +4,7 @@ build-backend = "setuptools.build_meta"
 
 [project]
 name = "pySEQTarget"
-version = "0.12.3"
+version = "0.12.4"
 description = "Sequentially Nested Target Trial Emulation"
 readme = "README.md"
 license = {text = "MIT"}