diff --git a/backend/src/core/config/environment.ts b/backend/src/core/config/environment.ts
index 6c6c5b2..ab46b8d 100644
--- a/backend/src/core/config/environment.ts
+++ b/backend/src/core/config/environment.ts
@@ -3,7 +3,7 @@
  * @ai-context Validates all env vars at startup, single source of truth
  */
 import { z } from 'zod';
-import dotenv from 'dotenv';
+import * as dotenv from 'dotenv';
 
 dotenv.config();
 
diff --git a/backend/src/core/logging/logger.ts b/backend/src/core/logging/logger.ts
index 02e4790..fded0cc 100644
--- a/backend/src/core/logging/logger.ts
+++ b/backend/src/core/logging/logger.ts
@@ -2,7 +2,7 @@
  * @ai-summary Structured logging with Winston
  * @ai-context All features use this for consistent logging
  */
-import winston from 'winston';
+import * as winston from 'winston';
 import { env, isDevelopment } from '../config/environment';
 
 export const logger = winston.createLogger({
diff --git a/backend/src/features/fuel-logs/domain/fuel-logs.service.ts b/backend/src/features/fuel-logs/domain/fuel-logs.service.ts
index 261fc1a..d20c7e7 100644
--- a/backend/src/features/fuel-logs/domain/fuel-logs.service.ts
+++ b/backend/src/features/fuel-logs/domain/fuel-logs.service.ts
@@ -87,7 +87,7 @@ export class FuelLogsService {
     
     // Get from database
     const logs = await this.repository.findByVehicleId(vehicleId);
-    const response = logs.map(log => this.toResponse(log));
+    const response = logs.map((log: FuelLog) => this.toResponse(log));
     
     // Cache result
     await cacheService.set(cacheKey, response, this.cacheTTL);
@@ -106,7 +106,7 @@ export class FuelLogsService {
     
     // Get from database
     const logs = await this.repository.findByUserId(userId);
-    const response = logs.map(log => this.toResponse(log));
+    const response = logs.map((log: FuelLog) => this.toResponse(log));
     
     // Cache result
     await cacheService.set(cacheKey, response, this.cacheTTL);
diff --git a/backend/src/features/stations/domain/stations.service.ts b/backend/src/features/stations/domain/stations.service.ts
index d0fb1a0..2eea95f 100644
--- a/backend/src/features/stations/domain/stations.service.ts
+++ b/backend/src/features/stations/domain/stations.service.ts
@@ -4,7 +4,7 @@
 
 import { StationsRepository } from '../data/stations.repository';
 import { googleMapsClient } from '../external/google-maps/google-maps.client';
-import { StationSearchRequest, StationSearchResponse } from './stations.types';
+import { StationSearchRequest, StationSearchResponse, SavedStation } from './stations.types';
 import { logger } from '../../../core/logging/logger';
 
 export class StationsService {
@@ -68,7 +68,7 @@ export class StationsService {
     
     // Enrich with cached station data
     const enriched = await Promise.all(
-      savedStations.map(async (saved) => {
+      savedStations.map(async (saved: SavedStation) => {
         const station = await this.repository.getCachedStation(saved.stationId);
         return {
           ...saved,
diff --git a/backend/src/features/vehicles/domain/vehicles.service.ts b/backend/src/features/vehicles/domain/vehicles.service.ts
index 05e5529..9db60dc 100644
--- a/backend/src/features/vehicles/domain/vehicles.service.ts
+++ b/backend/src/features/vehicles/domain/vehicles.service.ts
@@ -70,7 +70,7 @@ export class VehiclesService {
     
     // Get from database
     const vehicles = await this.repository.findByUserId(userId);
-    const response = vehicles.map(v => this.toResponse(v));
+    const response = vehicles.map((v: Vehicle) => this.toResponse(v));
     
     // Cache result
     await cacheService.set(cacheKey, response, this.listCacheTTL);