diff --git a/packages/twenty-server/src/integrations/environment/environment.validation.ts b/packages/twenty-server/src/integrations/environment/environment.validation.ts
index ea29dbe42..837a2975f 100644
--- a/packages/twenty-server/src/integrations/environment/environment.validation.ts
+++ b/packages/twenty-server/src/integrations/environment/environment.validation.ts
@@ -64,7 +64,7 @@ export class EnvironmentVariables {
   PORT: number;
 
   // Database
-  @IsUrl({ protocols: ['postgres'], require_tld: false })
+  @IsUrl({ protocols: ['postgres'], require_tld: false, allow_underscores: true })
   PG_DATABASE_URL: string;
 
   // Frontend URL