diff --git a/frontend/src/services/apiToken.test.ts b/frontend/src/services/apiToken.test.ts
new file mode 100644
index 000000000..c4be5d382
--- /dev/null
+++ b/frontend/src/services/apiToken.test.ts
@@ -0,0 +1,35 @@
+import {describe, it, expect} from 'vitest'
+
+import {objectToSnakeCase} from '@/helpers/case'
+
+// Regression test: objectToSnakeCase mangles hyphenated permission group
+// names like "time-entries" → "time_entries". ApiTokenService.beforeCreate
+// works around this by restoring the original permissions after the transform.
+// This test ensures the underlying problem is documented and will tell us
+// if the library behaviour changes.
+describe('objectToSnakeCase on API token permissions', () => {
+	it('mangles time-entries to time_entries (the bug we work around)', () => {
+		const input = {
+			title: 'test',
+			expiresAt: '2099-01-01T00:00:00Z',
+			permissions: {
+				'tasks': ['read_all', 'create'],
+				'time-entries': ['read_all', 'create'],
+				'tasks_assignees': ['create', 'delete'],
+			},
+		}
+
+		const result = objectToSnakeCase(input)
+
+		// The outer key is fine
+		expect(result.expires_at).toBe('2099-01-01T00:00:00Z')
+
+		// time-entries gets mangled — this is the bug
+		expect(result.permissions['time_entries']).toEqual(['read_all', 'create'])
+		expect(result.permissions['time-entries']).toBeUndefined()
+
+		// Other groups survive
+		expect(result.permissions['tasks']).toEqual(['read_all', 'create'])
+		expect(result.permissions['tasks_assignees']).toEqual(['create', 'delete'])
+	})
+})
diff --git a/frontend/src/services/apiToken.ts b/frontend/src/services/apiToken.ts
index 3f1914936..628dd91e0 100644
--- a/frontend/src/services/apiToken.ts
+++ b/frontend/src/services/apiToken.ts
@@ -1,6 +1,7 @@
 import AbstractService from '@/services/abstractService'
 import type {IApiToken} from '@/modelTypes/IApiToken'
 import ApiTokenModel from '@/models/apiTokenModel'
+import {objectToSnakeCase} from '@/helpers/case'
 
 export default class ApiTokenService extends AbstractService<IApiToken> {
 	constructor() {
@@ -11,6 +12,19 @@ export default class ApiTokenService extends AbstractService<IApiToken> {
 		})
 	}
 
+	// Disable the default snake_case transform — beforeCreate handles it
+	// manually to preserve the permissions map keys (e.g. "time-entries").
+	autoTransformBeforePut(): boolean {
+		return false
+	}
+
+	beforeCreate(model: IApiToken) {
+		const permissions = model.permissions
+		const transformed = objectToSnakeCase(model)
+		transformed.permissions = permissions
+		return transformed
+	}
+
 	processModel(model: IApiToken) {
 		return {
 			...model,
@@ -18,11 +32,11 @@ export default class ApiTokenService extends AbstractService<IApiToken> {
 			created: new Date(model.created).toISOString(),
 		}
 	}
-	
+
 	modelFactory(data: Partial<IApiToken>) {
 		return new ApiTokenModel(data)
 	}
-	
+
 	async getAvailableRoutes() {
 		const cancel = this.setLoading()