diff --git a/src/param/params-equation.ts b/src/param/params-equation.ts
index 5bc60a08d06df73e924cc5bbe828e92a03dfa71e..91a81b7115b5f5c9665d7e937171331a44675fe9 100644
--- a/src/param/params-equation.ts
+++ b/src/param/params-equation.ts
@@ -104,7 +104,9 @@ export abstract class ParamsEquation implements Iterable<ParamDefinition> {
     public constructor(parent?: ComputeNode) {
         this.parent = parent;
         this._calculabilityDefined = false;
-        this._Pr = new ParamDefinition(this, "Pr", ParamDomainValue.POS, ParamsEquation.DEFAULT_COMPUTE_PREC);
+        this._Pr = new ParamDefinition(
+            this, "Pr", ParamDomainValue.POS, ParamsEquation.DEFAULT_COMPUTE_PREC, undefined, false
+        );
         this.addParamDefinition(this._Pr);
     }