diff --git a/src/server.ts b/src/server.ts
index 620aaf3..82f27b3 100644
--- a/src/server.ts
+++ b/src/server.ts
@@ -4,7 +4,7 @@ import { GroupSyncService } from './services/group-sync';
 import { ResponseQueue } from './services/response-queue';
 import { WebhookManager } from './services/webhook-manager';
 import { normalizeWhatsAppId } from './utils/whatsapp';
-import { ensureUserExists } from './db';
+import { ensureUserExists, db } from './db';
 
 // Bun is available globally when running under Bun runtime
 declare global {
@@ -27,6 +27,8 @@ type WebhookPayload = {
 };
 
 export class WebhookServer {
+	static dbInstance: Database = db;
+
 	private static getBaseUrl(request: Request): string {
 		const proto = request.headers.get('x-forwarded-proto') || 'http';
 		const host = request.headers.get('x-forwarded-host') || request.headers.get('host');
@@ -119,7 +121,7 @@ export class WebhookServer {
 		}
 
 		// Ensure user exists in database
-		const userId = ensureUserExists(data.key.participant);
+		const userId = ensureUserExists(data.key.participant, WebhookServer.dbInstance);
 		if (!userId) {
 			if (process.env.NODE_ENV !== 'test') {
 				console.log('⚠️ Failed to ensure user exists, ignoring message');
diff --git a/tests/unit/server.test.ts b/tests/unit/server.test.ts
index 91ae843..2b9380d 100644
--- a/tests/unit/server.test.ts
+++ b/tests/unit/server.test.ts
@@ -26,6 +26,9 @@ beforeEach(() => {
   mockAdd = mock(() => Promise.resolve());
   ResponseQueue.add = mockAdd;
   
+  // Inject testDb for WebhookServer to use
+  WebhookServer.dbInstance = testDb;
+  
   // Ensure database is initialized (recreates tables if dropped)
   initializeDatabase(testDb);
   
@@ -373,9 +376,7 @@ describe('WebhookServer', () => {
           remoteJid: 'group-id@g.us',
           participant: 'sender-id@s.whatsapp.net'
         },
-        message: { 
-          conversation: `/tarea nueva Test task ${futureDate1} some text ${futureDate2}`
-        }
+        message: { conversation: `/tarea nueva Test task ${futureDate1} some text ${futureDate2}` }
       }
     };
     
@@ -401,9 +402,7 @@ describe('WebhookServer', () => {
           remoteJid: 'group-id@g.us',
           participant: 'sender-id@s.whatsapp.net'
         },
-        message: { 
-          conversation: `/tarea nueva Test task ${pastDate} more text ${futureDate}`
-        }
+        message: { conversation: `/tarea nueva Test task ${pastDate} more text ${futureDate}` }
       }
     };
     
@@ -429,9 +428,7 @@ describe('WebhookServer', () => {
           remoteJid: 'group-id@g.us',
           participant: 'sender-id@s.whatsapp.net'
         },
-        message: { 
-          conversation: `/tarea nueva Test task ${pastDate1} and ${pastDate2}`
-        }
+        message: { conversation: `/tarea nueva Test task ${pastDate1} and ${pastDate2}` }
       }
     };
     
@@ -456,9 +453,7 @@ describe('WebhookServer', () => {
           remoteJid: 'group-id@g.us',
           participant: 'sender-id@s.whatsapp.net'
         },
-        message: { 
-          conversation: `/tarea nueva Test task 2023-13-01 (invalid) ${futureDate} 25/12/2023 (invalid)`
-        }
+        message: { conversation: `/tarea nueva Test task 2023-13-01 (invalid) ${futureDate} 25/12/2023 (invalid)` }
       }
     };