diff --git a/src/Models/ThemeConfig/Conversion/AddPrefixToTagRenderingConfig.ts b/src/Models/ThemeConfig/Conversion/AddPrefixToTagRenderingConfig.ts
index 6aa347207..00019ff1f 100644
--- a/src/Models/ThemeConfig/Conversion/AddPrefixToTagRenderingConfig.ts
+++ b/src/Models/ThemeConfig/Conversion/AddPrefixToTagRenderingConfig.ts
@@ -111,7 +111,7 @@ export default class AddPrefixToTagRenderingConfig extends DesugaringStep<Questi
 
         return <QuestionableTagRenderingConfigJson>{
             ...json,
-            id: this._prefix + "_" + json.id,
+            id: this._prefix.replace(/[^a-zA-Z0-9_]/, "_") + "_" + json.id,
 
             question: this.updateTranslatable(json.question),
             questionHint: this.updateTranslatable(json.questionHint),