diff --git a/services/chrome-web-store/chrome-web-store-size.service.js b/services/chrome-web-store/chrome-web-store-size.service.js
index 040fc9a1a6d53..0a63adae19b39 100644
--- a/services/chrome-web-store/chrome-web-store-size.service.js
+++ b/services/chrome-web-store/chrome-web-store-size.service.js
@@ -22,8 +22,8 @@ export default class ChromeWebStoreSize extends BaseChromeWebStoreService {
     color: 'blue',
   }
 
-  transform(sizeStr) {
-    const match = sizeStr.match(/^(\d+)([a-zA-Z]+)$/)
+  static transform(sizeStr) {
+    const match = sizeStr.match(/^(\d+(?:\.\d+)?)([a-zA-Z]+)$/)
     if (!match) {
       throw new InvalidResponse({
         prettyMessage: 'size does not match expected format',
@@ -41,6 +41,6 @@ export default class ChromeWebStoreSize extends BaseChromeWebStoreService {
       throw new NotFound({ prettyMessage: 'not found' })
     }
 
-    return { message: this.transform(size) }
+    return { message: this.constructor.transform(size) }
   }
 }
diff --git a/services/chrome-web-store/chrome-web-store-size.spec.js b/services/chrome-web-store/chrome-web-store-size.spec.js
new file mode 100644
index 0000000000000..e7d940ca75732
--- /dev/null
+++ b/services/chrome-web-store/chrome-web-store-size.spec.js
@@ -0,0 +1,28 @@
+import { expect } from 'chai'
+import { test, given } from 'sazerac'
+import { InvalidResponse } from '../index.js'
+import ChromeWebStoreSize from './chrome-web-store-size.service.js'
+
+describe('transform function', function () {
+  it('formats size correctly', function () {
+    test(ChromeWebStoreSize.transform, () => {
+      given('0.55KiB').expect('0.55 KiB')
+      given('19.86KiB').expect('19.86 KiB')
+      given('432KiB').expect('432 KiB')
+    })
+  })
+
+  it('throws when the format is unexpected', function () {
+    expect(() => ChromeWebStoreSize.transform('432 KiB')).to.throw(
+      InvalidResponse,
+    )
+    expect(() => ChromeWebStoreSize.transform('432')).to.throw(InvalidResponse)
+    expect(() => ChromeWebStoreSize.transform('KiB')).to.throw(InvalidResponse)
+    expect(() => ChromeWebStoreSize.transform('foobar')).to.throw(
+      InvalidResponse,
+    )
+    expect(() => ChromeWebStoreSize.transform('4.4.4 KiB')).to.throw(
+      InvalidResponse,
+    )
+  })
+})