diff --git a/src/easyreflectometry/summary/summary.py b/src/easyreflectometry/summary/summary.py
index 89b82f48..cde96538 100644
--- a/src/easyreflectometry/summary/summary.py
+++ b/src/easyreflectometry/summary/summary.py
@@ -291,7 +291,9 @@ def _sample_section(self) -> str:
             html_parameter = html_parameter.replace('parameter_name', f'{name}')
             html_parameter = html_parameter.replace('parameter_value', _format_value(value, 3))
             html_parameter = html_parameter.replace('parameter_unit', f'{unit}')
-            error_str = _format_value(error, 2)
+            # An unfitted parameter has no uncertainty; a literal '0.0' would
+            # read as a perfectly determined value, so leave the cell empty.
+            error_str = _format_value(error, 2) if error else ''
             html_parameter = html_parameter.replace('parameter_error', error_str)
             html_parameters.append(html_parameter)