diff --git a/src/client.ts b/src/client.ts
index a8021af..e7dc6ba 100644
--- a/src/client.ts
+++ b/src/client.ts
@@ -23,16 +23,22 @@ export interface ClientOptions {
 export class Client {
   private apiURL?: string
   private edgeURL?: string
-  private fetch?: Fetcher
+  private fetch: Fetcher
   private siteID: string
   private token: string
 
   constructor({ apiURL, edgeURL, fetch, siteID, token }: ClientOptions) {
     this.apiURL = apiURL
     this.edgeURL = edgeURL
-    this.fetch = fetch
+    this.fetch = fetch ?? globalThis.fetch
     this.siteID = siteID
     this.token = token
+
+    if (!this.fetch) {
+      throw new Error(
+        'Netlify Blobs could not find a `fetch` client in the global scope. You can either update your runtime to a version that includes `fetch` (like Node.js 18.0.0 or above), or you can supply your own implementation using the `fetch` property.',
+      )
+    }
   }
 
   private async getFinalRequest(storeName: string, key: string, method: string, metadata?: Metadata) {
@@ -63,8 +69,7 @@ export class Client {
       apiHeaders[METADATA_HEADER_EXTERNAL] = encodedMetadata
     }
 
-    const fetch = this.fetch ?? globalThis.fetch
-    const res = await fetch(apiURL, { headers: apiHeaders, method })
+    const res = await this.fetch(apiURL, { headers: apiHeaders, method })
 
     if (res.status !== 200) {
       throw new Error(`${method} operation has failed: API returned a ${res.status} response`)
@@ -102,8 +107,7 @@ export class Client {
       options.duplex = 'half'
     }
 
-    const fetch = this.fetch ?? globalThis.fetch
-    const res = await fetchAndRetry(fetch, url, options)
+    const res = await fetchAndRetry(this.fetch, url, options)
 
     if (res.status === 404 && method === HTTPMethod.GET) {
       return null
diff --git a/src/main.test.ts b/src/main.test.ts
index a0a714b..31bb1b9 100644
--- a/src/main.test.ts
+++ b/src/main.test.ts
@@ -1120,4 +1120,71 @@ describe(`getStore`, () => {
       'The `getStore` method requires the name of the store as a string or as the `name` property of an options object',
     )
   })
+
+  test('Throws when the name of the store starts with the `deploy:` prefix', async () => {
+    const { fetch } = new MockFetch()
+
+    globalThis.fetch = fetch
+
+    expect(() =>
+      getStore({
+        name: 'deploy:foo',
+        token: apiToken,
+        siteID,
+      }),
+    ).toThrowError('Store name cannot start with the string `deploy:`, which is a reserved namespace')
+
+    const context = {
+      siteID,
+      token: apiToken,
+    }
+
+    env.NETLIFY_BLOBS_CONTEXT = Buffer.from(JSON.stringify(context)).toString('base64')
+
+    expect(() => getStore('deploy:foo')).toThrowError(
+      'Store name cannot start with the string `deploy:`, which is a reserved namespace',
+    )
+  })
+
+  test('Throws when there is no `fetch` implementation available', async () => {
+    // @ts-expect-error Assigning a value that doesn't match the type.
+    globalThis.fetch = undefined
+
+    const context = {
+      siteID,
+      token: apiToken,
+    }
+
+    env.NETLIFY_BLOBS_CONTEXT = Buffer.from(JSON.stringify(context)).toString('base64')
+
+    expect(() => getStore('production')).toThrowError(
+      'Netlify Blobs could not find a `fetch` client in the global scope. You can either update your runtime to a version that includes `fetch` (like Node.js 18.0.0 or above), or you can supply your own implementation using the `fetch` property.',
+    )
+  })
+
+  test('URL-encodes the store name', async () => {
+    const mockStore = new MockFetch()
+      .get({
+        headers: { authorization: `Bearer ${apiToken}` },
+        response: new Response(JSON.stringify({ url: signedURL })),
+        url: `https://api.netlify.com/api/v1/sites/${siteID}/blobs/${key}?context=%2Fwhat%3F`,
+      })
+      .get({
+        response: new Response(value),
+        url: signedURL,
+      })
+
+    globalThis.fetch = mockStore.fetch
+
+    const blobs = getStore({
+      name: '/what?',
+      token: apiToken,
+      siteID,
+    })
+
+    const string = await blobs.get(key)
+    expect(string).toBe(value)
+
+    expect(mockStore.fulfilled).toBeTruthy()
+  })
 })
diff --git a/src/store.ts b/src/store.ts
index bf3be46..bd94d9d 100644
--- a/src/store.ts
+++ b/src/store.ts
@@ -33,7 +33,14 @@ export class Store {
 
   constructor(options: StoreOptions) {
     this.client = options.client
-    this.name = 'deployID' in options ? `deploy:${options.deployID}` : options.name
+
+    if ('deployID' in options) {
+      this.name = `deploy:${encodeURIComponent(options.deployID)}`
+    } else if (options?.name.startsWith('deploy:')) {
+      throw new Error('Store name cannot start with the string `deploy:`, which is a reserved namespace')
+    } else {
+      this.name = encodeURIComponent(options.name)
+    }
   }
 
   async delete(key: string) {