diff --git a/lib/attachments/gridstore-storage.js b/lib/attachments/gridstore-storage.js
index 87bb5020..4498496c 100644
--- a/lib/attachments/gridstore-storage.js
+++ b/lib/attachments/gridstore-storage.js
@@ -7,6 +7,7 @@ const errors = require('../errors');
 const log = require('npmlog');
 const crypto = require('crypto');
 const base64Offset = require('./base64-offset');
+const Transform = require('stream').Transform;
 
 // Set to false to disable base64 decoding feature
 const FEATURE_DECODE_ATTACHMENTS = true;
@@ -14,6 +15,40 @@ const FEATURE_DECODE_ATTACHMENTS = true;
 const ORPHANED_ATTACHMENTS_DELAY = 24 * 3600 * 1000;
 const MAX_ORPHANED_ATTACHMENTS = 1000;
 
+class FileHashCalculator extends Transform {
+    constructor(options) {
+        super(options);
+        this.bodyHash = crypto.createHash('sha256');
+        this.hash = null;
+    }
+
+    updateHash(chunk) {
+        this.bodyHash.update(chunk);
+    }
+
+    _transform(chunk, encoding, callback) {
+        if (!chunk || !chunk.length) {
+            return callback();
+        }
+
+        if (typeof chunk === 'string') {
+            chunk = Buffer.from(chunk, encoding);
+        }
+
+        this.updateHash(chunk);
+        this.push(chunk);
+
+        callback();
+    }
+
+    _flush(done) {
+        this.hash = this.bodyHash.digest('base64');
+        done();
+    }
+}
+
+let fileHashCalculator = new FileHashCalculator();
+
 class GridstoreStorage {
     constructor(options) {
         this.bucketName = (options.options && options.options.bucket) || 'attachments';
@@ -129,6 +164,35 @@ class GridstoreStorage {
         let storeLock;
 
         let attachmentCallback = (...args) => {
+            // store finished uploading, add the hash of the file contents to file metadata
+            if (args.length > 2) {
+                const calculatedFileContentHash = args[2];
+
+                this.gridfs.collection(this.bucketName + '.files').findOneAndUpdate(
+                    {
+                        _id: hash
+                    },
+                    {
+                        $set: {
+                            'metadata.fileContentHash': calculatedFileContentHash
+                        }
+                    },
+                    {
+                        returnDocument: 'after'
+                    },
+                    (err, res) => {
+                        if (err) {
+                            return attachmentCallback(err);
+                        }
+
+                        if (res && res.value && res.value.metadata.fileContentHash && res.value.metadata.fileContentHash === calculatedFileContentHash) {
+                            // all good?
+                            // do nothing
+                        }
+                    }
+                );
+            }
+
             if (storeLock) {
                 log.silly('GridStore', '[%s] UNLOCK lock=%s status=%s', instance, lockId, storeLock.success ? 'locked' : 'empty');
                 if (storeLock.success) {
@@ -282,13 +346,13 @@ class GridstoreStorage {
                             attachmentCallback(err);
                         });
 
-                        store.once('finish', () => attachmentCallback(null, id));
+                        store.once('finish', () => attachmentCallback(null, id, fileHashCalculator.hash));
 
                         if (!metadata.decoded) {
                             store.end(attachment.body);
                         } else {
                             let decoder = new libbase64.Decoder();
-                            decoder.pipe(store);
+                            decoder.pipe(fileHashCalculator).pipe(store);
                             decoder.once('error', err => {
                                 // pass error forward
                                 store.emit('error', err);