diff --git a/src/geophires_x/Outputs.py b/src/geophires_x/Outputs.py
index b262ce1a..271c7bac 100644
--- a/src/geophires_x/Outputs.py
+++ b/src/geophires_x/Outputs.py
@@ -716,7 +716,7 @@ def read_parameters(self, model: Model, default_output_path: Path = None) -> Non
                         if not Path(ParameterReadIn.sValue).is_absolute() and default_output_path is not None:
                             original_val = ParameterReadIn.sValue
                             ParameterReadIn.sValue = str(
-                                default_output_path.joinpath(ParameterReadIn.sValue).absolute())
+                                default_output_path.joinpath(Path(ParameterReadIn.sValue)).absolute())
                             model.logger.info(f'Adjusted {key} path to {ParameterReadIn.sValue} because original value '
                                               f'({original_val}) was not an absolute path.')
 
diff --git a/tests/geophires_x_tests/test_outputs.py b/tests/geophires_x_tests/test_outputs.py
new file mode 100644
index 00000000..8d06e4ae
--- /dev/null
+++ b/tests/geophires_x_tests/test_outputs.py
@@ -0,0 +1,45 @@
+import os
+import sys
+from pathlib import Path
+
+from geophires_x.Model import Model
+from geophires_x_client import GeophiresInputParameters
+from tests.base_test_case import BaseTestCase
+
+
+class OutputsTestCase(BaseTestCase):
+
+    def test_relative_output_file_path(self):
+        input_file = GeophiresInputParameters({'HTML Output File': 'foo.html'}).as_file_path()
+        m = self._new_model(input_file=input_file, original_cwd=Path('/tmp/'))  # noqa: S108
+        html_filepath = Path(m.outputs.html_output_file.value)
+        self.assertTrue(html_filepath.is_absolute())
+        self.assertEqual(str(html_filepath), '/tmp/foo.html')  # noqa: S108
+
+    def test_absolute_output_file_path(self):
+        input_file = GeophiresInputParameters(
+            {'HTML Output File': '/home/user/my-geophires-project/foo.html'}
+        ).as_file_path()
+        m = self._new_model(input_file=input_file, original_cwd=Path('/tmp/'))  # noqa: S108
+        html_filepath = Path(m.outputs.html_output_file.value)
+        self.assertTrue(html_filepath.is_absolute())
+        self.assertEqual(str(html_filepath), '/home/user/my-geophires-project/foo.html')
+
+    def _new_model(self, input_file=None, original_cwd=None) -> Model:
+        stash_cwd = Path.cwd()
+        stash_sys_argv = sys.argv
+
+        sys.argv = ['']
+
+        if input_file is not None:
+            sys.argv.append(input_file)
+
+        m = Model(enable_geophires_logging_config=False)
+
+        if input_file is not None:
+            m.read_parameters(default_output_path=original_cwd)
+
+        sys.argv = stash_sys_argv
+        os.chdir(stash_cwd)
+
+        return m