diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index edb7af3d..4ebb5bb9 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -2,6 +2,10 @@
 Changelog
 =========
 
+(Development) Version 1.1.3
+===========================
+- Lock pandas to 2.1.4 or later
+
 Version 1.1.2
 =============
 - Update zenodo metadata for JOSS
diff --git a/docs/requirements.txt b/docs/requirements.txt
index 6b659fb8..335ad615 100644
--- a/docs/requirements.txt
+++ b/docs/requirements.txt
@@ -4,7 +4,7 @@ flatten_dict
 Jinja2<3.1
 networkx
 openpyxl
-pandas>=1.1,<2.1
+pandas>=2.1.4
 pydantic>=2
 pydot
 pyyaml
diff --git a/setup.cfg b/setup.cfg
index 7fbcbb43..50272515 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -47,7 +47,7 @@ install_requires =
     xlrd
     pyyaml
     pydot
-    pandas>=1.1,<2.1
+    pandas>=2.1.4
     Amply>=0.1.6
     networkx
     flatten_dict
diff --git a/src/otoole/input.py b/src/otoole/input.py
index b3c979c7..210647a2 100644
--- a/src/otoole/input.py
+++ b/src/otoole/input.py
@@ -341,8 +341,11 @@ def _expand_defaults(
             df_default["VALUE"] = default_values[name]
 
             # combine result and default value dataframe
-            df = pd.concat([data, df_default])
-            df = df[~df.index.duplicated(keep="first")]
+            if not data.empty:
+                df = pd.concat([data, df_default])
+                df = df[~df.index.duplicated(keep="first")]
+            else:
+                df = df_default
             df = df.sort_index()
             output[name] = df
 
diff --git a/tests/test_input.py b/tests/test_input.py
index 292e4309..e9a7b148 100644
--- a/tests/test_input.py
+++ b/tests/test_input.py
@@ -265,7 +265,7 @@ def result_data(region):
         input_data_single_index_empty(region),
     ]
     parameter_test_data_ids = [
-        "multi_index_no_defaluts",
+        "multi_index_no_defaults",
         "multi_index",
         "multi_index_empty",
         "single_index",