diff --git a/src/secure-dfu.ts b/src/secure-dfu.ts
index dd010cd..b4fbf8d 100644
--- a/src/secure-dfu.ts
+++ b/src/secure-dfu.ts
@@ -148,8 +148,11 @@ export class SecureDfu extends EventDispatcher {
      * Characteristic constructor
      * @param bluetooth A bluetooth instance
      * @param crc32 A CRC32 function
+     * @param delay Milliseconds of delay between packets
      */
-    constructor(private crc32: (data: Array<number> | Uint8Array, seed?: number) => number, private bluetooth?: Bluetooth) {
+    constructor(private crc32: (data: Array<number> | Uint8Array, seed?: number) => number,
+                private bluetooth?: Bluetooth,
+                private delay: number = 0) {
         super();
 
         if (!this.bluetooth && window && window.navigator && window.navigator.bluetooth) {
@@ -361,6 +364,7 @@ export class SecureDfu extends EventDispatcher {
         const packet = data.slice(start, end);
 
         return this.packetChar.writeValue(packet)
+        .then(this.delayPromise(this.delay))
         .then(() => {
             this.progress(offset + end);
 
@@ -379,6 +383,16 @@ export class SecureDfu extends EventDispatcher {
         return crc === this.crc32(new Uint8Array(buffer));
     }
 
+    private delayPromise(delay: number) {
+        return data => {
+            return new Promise((resolve, _) => {
+                setTimeout(() => {
+                    resolve(data);
+                }, delay);
+            });
+        };
+    }
+
     /**
      * Scans for a device to update
      * @param buttonLess Scans for all devices and will automatically call `setDfuMode`