diff --git a/flepimop/gempyor_pkg/src/gempyor/inference_parameter.py b/flepimop/gempyor_pkg/src/gempyor/inference_parameter.py
index 2244748ce..612835e9e 100644
--- a/flepimop/gempyor_pkg/src/gempyor/inference_parameter.py
+++ b/flepimop/gempyor_pkg/src/gempyor/inference_parameter.py
@@ -53,8 +53,8 @@ def add_modifier(self, pname, ptype, parameter_config, subpops):
                     pname=pname,
                     subpop=sp,
                     pdist=parameter_config["value"].as_random_distribution(),
-                    lb=float(parameter_config["value"]["a"].get()),
-                    ub=float(parameter_config["value"]["b"].get()),
+                    lb=parameter_config["value"]["a"].get(float),
+                    ub=parameter_config["value"]["b"].get(float),
                 )
 
         # grouped subpop have one parameter per group