diff --git a/apps/backend/src/app/machines/machines.service.ts b/apps/backend/src/app/machines/machines.service.ts
index 9ea6605..37a9e64 100644
--- a/apps/backend/src/app/machines/machines.service.ts
+++ b/apps/backend/src/app/machines/machines.service.ts
@@ -8,6 +8,7 @@ import {
 	FilesForMachinesTable,
 	FilesTable,
 	FilesTypeForMachine,
+	FilesTypesTable,
 	MachinesTable,
 } from "apps/backend/src/app/db/schema";
 import { and, eq, ilike } from "drizzle-orm";
@@ -80,7 +81,6 @@ export class MachinesService {
 	 * @throws {NotFoundException} If the machine ID or file type ID is not found.
 	 */
 	async removeFileType(machineId: string, fileTypeId: string) {
-		//TODO Find machineId
 		const machine = await this.database
 			.use()
 			.select()
@@ -90,7 +90,7 @@ export class MachinesService {
 			.execute();
 		if (machine.length !== 1)
 			throw new NotFoundException("Machine id not found.");
-		//TODO Find fileTypeId
+
 		const fileType = await this.database
 			.use()
 			.select()
@@ -120,9 +120,45 @@ export class MachinesService {
 		return fileType;
 	}
 
+	/**
+	 * Adds a file type to a machine by their respective IDs.
+	 *
+	 * @param {string} machineId - The ID of the machine to which the file type will be added.
+	 * @param {string} fileTypeId - The ID of the file type to be added to the machine.
+	 * @return {Promise<object>} The result of the database insert operation.
+	 * @throws {NotFoundException} If the machine ID or file type ID are not found in the database.
+	 */
 	async addFileType(machineId: string, fileTypeId: string) {
-		//TODO Find machineId
-		//TODO Find fileTypeId
+		const machine = await this.database
+			.use()
+			.select()
+			.from(MachinesTable)
+			.where(eq(MachinesTable.id, machineId))
+			.prepare("findMachineById")
+			.execute();
+		if (machine.length !== 1)
+			throw new NotFoundException("Machine id not found.");
+
+		const fileType = await this.database
+			.use()
+			.select()
+			.from(FilesTypesTable)
+			.where(eq(FilesTypesTable.id, fileTypeId))
+			.prepare("findFileTypeById")
+			.execute();
+		if (fileType.length !== 1)
+			throw new NotFoundException("File type not found.");
+
+		const insertFileType = await this.database
+			.use()
+			.insert(FilesTypeForMachine)
+			.values({
+				machineId,
+				fileTypeId,
+			})
+			.prepare("insertFileTypeForMachine")
+			.execute();
+		return insertFileType;
 	}
 
 	async getFilesTypes(machineId: string) {