diff --git a/src/app/core/substance-form/substance-form-definition/substance-form-definition.component.ts b/src/app/core/substance-form/substance-form-definition/substance-form-definition.component.ts
index 64af9d315..16993db82 100644
--- a/src/app/core/substance-form/substance-form-definition/substance-form-definition.component.ts
+++ b/src/app/core/substance-form/substance-form-definition/substance-form-definition.component.ts
@@ -85,6 +85,7 @@ export class SubstanceFormDefinitionComponent extends SubstanceFormBase implemen
       this.definition = definition || {};
       if (definition && definition.substanceClass && (definition.substanceClass === 'polymer' || definition.substanceClass === 'mixture') && !definition.uuid) {
         this.definition.definitionLevel = 'REPRESENTATIVE';
+        this.updateDefinition();
       }
       this.crossCheckTags();
       if (this.definition.substanceClass === 'structure') {