diff --git a/src/Connector.js b/src/Connector.js
index 2e65103c..3a22d776 100644
--- a/src/Connector.js
+++ b/src/Connector.js
@@ -181,10 +181,16 @@ export default function extendConnector (Y/* :any */) {
       }
     }
     send (uid, buffer) {
+      if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
+        throw new Error('Expected Message to be an ArrayBuffer or Uint8Array - please don\'t use this method to send custom messages')
+      }
       this.log('%s: Send \'%y\' to %s', this.userId, buffer, uid)
       this.logMessage('Message: %Y', buffer)
     }
     broadcast (buffer) {
+      if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
+        throw new Error('Expected Message to be an ArrayBuffer or Uint8Array - please don\'t use this method to send custom messages')
+      }
       this.log('%s: Broadcast \'%y\'', this.userId, buffer)
       this.logMessage('Message: %Y', buffer)
     }
@@ -223,6 +229,9 @@ export default function extendConnector (Y/* :any */) {
       You received a raw message, and you know that it is intended for Yjs. Then call this function.
     */
     async receiveMessage (sender, buffer) {
+      if (!(buffer instanceof ArrayBuffer || buffer instanceof Uint8Array)) {
+        throw new Error('Expected Message to be an ArrayBuffer or Uint8Array!')
+      }
       if (sender === this.userId) {
         return
       }
diff --git a/src/Encoding.js b/src/Encoding.js
index f759a421..2308d22e 100644
--- a/src/Encoding.js
+++ b/src/Encoding.js
@@ -66,7 +66,13 @@ export class BinaryEncoder {
 
 export class BinaryDecoder {
   constructor (buffer) {
-    this.uint8arr = new Uint8Array(buffer)
+    if (buffer instanceof ArrayBuffer) {
+      this.uint8arr = new Uint8Array(buffer)
+    } else if (buffer instanceof Uint8Array) {
+      this.uint8arr = buffer
+    } else {
+      throw new Error('Expected an ArrayBuffer or Uint8Array!')
+    }
     this.pos = 0
   }
   skip8 () {
diff --git a/test/encode-decode.js b/test/encode-decode.js
index 53b1550c..7b9570ab 100644
--- a/test/encode-decode.js
+++ b/test/encode-decode.js
@@ -227,4 +227,3 @@ test('encode/decode Map operations', async function binMap (t) {
     info: 400
   })
 })
-