diff --git a/src/jimgw/single_event/runManager.py b/src/jimgw/single_event/runManager.py
index c1439b39..3e5bc092 100644
--- a/src/jimgw/single_event/runManager.py
+++ b/src/jimgw/single_event/runManager.py
@@ -195,6 +195,7 @@ def initialize_prior(self) -> prior.CombinePrior:
                     prior_class = getattr(prior, parameters["name"])
                 except AttributeError:
                     raise ValueError(f"{parameters['name']} not recognized.")
+            parameters = parameters.copy()
             parameters.pop("name")
             priors.append(prior_class(parameter_names=[name], **parameters))
         return prior.CombinePrior(priors)