diff --git a/changelog.md b/changelog.md
index fcf721b..06c42e9 100644
--- a/changelog.md
+++ b/changelog.md
@@ -1,5 +1,11 @@
 # graphql-upload changelog
 
+## Next
+
+### Patch
+
+- Handle invalid object paths in `map` multipart field entries, fixing [#154](https://github.com/jaydenseric/graphql-upload/issues/154).
+
 ## 8.0.6
 
 ### Patch
diff --git a/src/processRequest.mjs b/src/processRequest.mjs
index 198ae26..cdfb688 100644
--- a/src/processRequest.mjs
+++ b/src/processRequest.mjs
@@ -271,7 +271,16 @@ export const processRequest = (
                   )
                 )
 
-              operationsPath.set(path, map.get(fieldName).promise)
+              try {
+                operationsPath.set(path, map.get(fieldName).promise)
+              } catch (error) {
+                return exit(
+                  createError(
+                    400,
+                    `Invalid object path for the ‘map’ multipart field entry key ‘${fieldName}’ array index ‘${index}’ value ‘${path}’ (${SPEC_URL}).`
+                  )
+                )
+              }
             }
           }
 
diff --git a/src/test.mjs b/src/test.mjs
index d5cc660..d7250e0 100644
--- a/src/test.mjs
+++ b/src/test.mjs
@@ -537,6 +537,53 @@ t.test('Invalid ‘map’ entry array item type.', async t => {
   })
 })
 
+t.test('Invalid ‘map’ entry object path.', async t => {
+  const sendRequest = async (t, port) => {
+    const body = new FormData()
+
+    body.append('operations', '{ "variables": "" }')
+    body.append('map', '{ "1": ["variables.file"] }')
+    body.append('1', 'a', { filename: 'a.txt' })
+
+    const { status } = await fetch(`http://localhost:${port}`, {
+      method: 'POST',
+      body
+    })
+
+    t.equal(status, 400, 'Response status.')
+  }
+
+  await t.test('Koa middleware.', async t => {
+    t.plan(2)
+
+    const app = new Koa()
+      .on('error', error =>
+        t.matchSnapshot(snapshotError(error), 'Middleware throws.')
+      )
+      .use(graphqlUploadKoa())
+
+    const port = await startServer(t, app)
+
+    await sendRequest(t, port)
+  })
+
+  await t.test('Express middleware.', async t => {
+    t.plan(2)
+
+    const app = express()
+      .use(graphqlUploadExpress())
+      .use((error, request, response, next) => {
+        if (response.headersSent) return next(error)
+        t.matchSnapshot(snapshotError(error), 'Middleware throws.')
+        response.send()
+      })
+
+    const port = await startServer(t, app)
+
+    await sendRequest(t, port)
+  })
+})
+
 t.test('Handles unconsumed uploads.', async t => {
   const sendRequest = async port => {
     const body = new FormData()
diff --git a/tap-snapshots/lib-test-TAP.test.js b/tap-snapshots/lib-test-TAP.test.js
index e391b1d..6eb5302 100644
--- a/tap-snapshots/lib-test-TAP.test.js
+++ b/tap-snapshots/lib-test-TAP.test.js
@@ -347,6 +347,26 @@ exports[`lib/test TAP Invalid ‘map’ entry array item type. Koa middleware. >
 }
 `
 
+exports[`lib/test TAP Invalid ‘map’ entry object path. Express middleware. > Middleware throws. 1`] = `
+{
+  "name": "BadRequestError",
+  "message": "Invalid object path for the ‘map’ multipart field entry key ‘1’ array index ‘0’ value ‘variables.file’ (https://github.com/jaydenseric/graphql-multipart-request-spec).",
+  "status": 400,
+  "statusCode": 400,
+  "expose": true
+}
+`
+
+exports[`lib/test TAP Invalid ‘map’ entry object path. Koa middleware. > Middleware throws. 1`] = `
+{
+  "name": "BadRequestError",
+  "message": "Invalid object path for the ‘map’ multipart field entry key ‘1’ array index ‘0’ value ‘variables.file’ (https://github.com/jaydenseric/graphql-multipart-request-spec).",
+  "status": 400,
+  "statusCode": 400,
+  "expose": true
+}
+`
+
 exports[`lib/test TAP Invalid ‘map’ entry type. Express middleware. > Middleware throws. 1`] = `
 {
   "name": "BadRequestError",