diff --git a/src/__tests__/scales/polish.ts b/src/__tests__/scales/polish.ts
index eaa38a2..af423cc 100644
--- a/src/__tests__/scales/polish.ts
+++ b/src/__tests__/scales/polish.ts
@@ -3,8 +3,11 @@ import { Polish } from '../../scales'
 
 describe('Polish', () => {
   describe('isPolish', () => {
-    test('VI', () => {
-      expect(Polish.isType('VI'))
+    test('VI is a valid grade', () => {
+      expect(Polish.isType('VI')).toBe(true)
+    })
+    test('asd is not a valid grade', () => {
+      expect(Polish.isType('asd')).toBe(false)
     })
   })
   // describe('Get Score', () => {
diff --git a/src/scales/polish.ts b/src/scales/polish.ts
index 7dc1f79..a8d8e87 100644
--- a/src/scales/polish.ts
+++ b/src/scales/polish.ts
@@ -3,11 +3,7 @@ import routes from '../data/routes.json'
 import { Route } from '.'
 import { GradeBandTypes, routeScoreToBand } from '../GradeBands'
 
-// TODO: set this regexp
-const polishGradeRegex = /^([1-9][a-c][+]?){1}(?:(\/)([1-9][a-c][+]?))?$/i
-// Supports 1a -> 9c+, slash grades i.e. 5a/5a+ or 6a+/6b
-// NOTE: this currently assumes "incorrect" slash grades follows the normal pattern
-// i.e. 6b+/5a => 6b+/6c
+const polishGradeRegex = /^((I{1,3})|(IV\+?)|(V[+,-]?)|(VI(.[1-9])?\+?))?$/i
 const isPolish = (grade: string): RegExpMatchArray | null => grade.match(polishGradeRegex)
 
 const PolishScale: GradeScale = {