diff --git a/app/lib/pty.ts b/app/lib/pty.ts
index 14ed60f3..e0e53eb9 100644
--- a/app/lib/pty.ts
+++ b/app/lib/pty.ts
@@ -105,7 +105,7 @@ export class PTY {
 
     write (buffer: Buffer): void {
         if ((this.pty as any)._writable) {
-            this.pty.write(buffer.toString())
+            this.pty.write(buffer as any)
         }
     }
 
diff --git a/app/lib/stringDecoder.ts b/app/lib/stringDecoder.ts
new file mode 100644
index 00000000..3583c6bc
--- /dev/null
+++ b/app/lib/stringDecoder.ts
@@ -0,0 +1,148 @@
+// based on Joyent's StringDecoder
+// https://github.com/nodejs/string_decoder/blob/master/lib/string_decoder.js
+
+export class StringDecoder {
+    lastNeed: number
+    lastTotal: number
+    lastChar: Buffer
+
+    constructor () {
+        this.lastNeed = 0
+        this.lastTotal = 0
+        this.lastChar = Buffer.allocUnsafe(4)
+    }
+
+    write (buf: Buffer): Buffer {
+        if (buf.length === 0) {
+            return buf
+        }
+        let r: Buffer|undefined = undefined
+        let i = 0
+        if (this.lastNeed) {
+            r = this.fillLast(buf)
+            if (r === undefined) {
+                return Buffer.from('')
+            }
+            i = this.lastNeed
+            this.lastNeed = 0
+        }
+        if (i < buf.length) {
+            return r ? Buffer.concat([r, this.text(buf, i)]) : this.text(buf, i)
+        }
+        return r
+    }
+
+    // For UTF-8, a replacement character is added when ending on a partial
+    // character.
+    end (buf?: Buffer): Buffer {
+        const r = buf?.length ? this.write(buf) : Buffer.from('')
+        if (this.lastNeed) {
+            console.log('end', r)
+            return Buffer.concat([r, Buffer.from('\ufffd')])
+        }
+        return r
+    }
+
+    // Returns all complete UTF-8 characters in a Buffer. If the Buffer ended on a
+    // partial character, the character's bytes are buffered until the required
+    // number of bytes are available.
+    private text (buf: Buffer, i: number) {
+        const total = this.utf8CheckIncomplete(buf, i)
+        if (!this.lastNeed) {
+            return buf.slice(i)
+        }
+        this.lastTotal = total
+        const end = buf.length - (total - this.lastNeed)
+        buf.copy(this.lastChar, 0, end)
+        return buf.slice(i, end)
+    }
+
+    // Attempts to complete a partial non-UTF-8 character using bytes from a Buffer
+    private fillLast (buf: Buffer): Buffer|undefined {
+        if (this.lastNeed <= buf.length) {
+            buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, this.lastNeed)
+            return this.lastChar.slice(0, this.lastTotal)
+        }
+        buf.copy(this.lastChar, this.lastTotal - this.lastNeed, 0, buf.length)
+        this.lastNeed -= buf.length
+        return undefined
+    }
+
+    // Checks the type of a UTF-8 byte, whether it's ASCII, a leading byte, or a
+    // continuation byte. If an invalid byte is detected, -2 is returned.
+    private utf8CheckByte (byte) {
+        if (byte <= 0x7F) {return 0} else if (byte >> 5 === 0x06) {return 2} else if (byte >> 4 === 0x0E) {return 3} else if (byte >> 3 === 0x1E) {return 4}
+        return byte >> 6 === 0x02 ? -1 : -2
+    }
+
+    // Checks at most 3 bytes at the end of a Buffer in order to detect an
+    // incomplete multi-byte UTF-8 character. The total number of bytes (2, 3, or 4)
+    // needed to complete the UTF-8 character (if applicable) are returned.
+    private utf8CheckIncomplete (buf, i) {
+        let j = buf.length - 1
+        if (j < i) {return 0}
+        let nb = this.utf8CheckByte(buf[j])
+        if (nb >= 0) {
+            if (nb > 0) {this.lastNeed = nb - 1}
+            return nb
+        }
+        if (--j < i || nb === -2) {return 0}
+        nb = this.utf8CheckByte(buf[j])
+        if (nb >= 0) {
+            if (nb > 0) {this.lastNeed = nb - 2}
+            return nb
+        }
+        if (--j < i || nb === -2) {return 0}
+        nb = this.utf8CheckByte(buf[j])
+        if (nb >= 0) {
+            if (nb > 0) {
+                if (nb === 2) {nb = 0} else {this.lastNeed = nb - 3}
+            }
+            return nb
+        }
+        return 0
+    }
+}
+
+
+
+
+// // Validates as many continuation bytes for a multi-byte UTF-8 character as
+// // needed or are available. If we see a non-continuation byte where we expect
+// // one, we "replace" the validated continuation bytes we've seen so far with
+// // a single UTF-8 replacement character ('\ufffd'), to match v8's UTF-8 decoding
+// // behavior. The continuation byte check is included three times in the case
+// // where all of the continuation bytes for a character exist in the same buffer.
+// // It is also done this way as a slight performance increase instead of using a
+// // loop.
+// function utf8CheckExtraBytes (self, buf, p) {
+//     if ((buf[0] & 0xC0) !== 0x80) {
+//         self.lastNeed = 0
+//         return '\ufffd'
+//     }
+//     if (self.lastNeed > 1 && buf.length > 1) {
+//         if ((buf[1] & 0xC0) !== 0x80) {
+//             self.lastNeed = 1
+//             return '\ufffd'
+//         }
+//         if (self.lastNeed > 2 && buf.length > 2) {
+//             if ((buf[2] & 0xC0) !== 0x80) {
+//                 self.lastNeed = 2
+//                 return '\ufffd'
+//             }
+//         }
+//     }
+// }
+
+// // Attempts to complete a multi-byte UTF-8 character using bytes from a Buffer.
+// function utf8FillLast (buf) {
+//     const p = this.lastTotal - this.lastNeed
+//     const r = utf8CheckExtraBytes(this, buf, p)
+//     if (r !== undefined) {return r}
+//     if (this.lastNeed <= buf.length) {
+//         buf.copy(this.lastChar, p, 0, this.lastNeed)
+//         return this.lastChar.toString(this.encoding, 0, this.lastTotal)
+//     }
+//     buf.copy(this.lastChar, p, 0, buf.length)
+//     this.lastNeed -= buf.length
+// }
diff --git a/terminus-terminal/src/features/zmodem.ts b/terminus-terminal/src/features/zmodem.ts
index 8ee0049b..d091501e 100644
--- a/terminus-terminal/src/features/zmodem.ts
+++ b/terminus-terminal/src/features/zmodem.ts
@@ -50,23 +50,35 @@ export class ZModemDecorator extends TerminalDecorator {
             },
         })
         setTimeout(() => {
-            this.subscribeUntilDetached(terminal, terminal.session!.binaryOutput$.subscribe(data => {
-                const chunkSize = 1024
-                for (let i = 0; i <= Math.floor(data.length / chunkSize); i++) {
-                    try {
-                        sentry.consume(data.subarray(i * chunkSize, (i + 1) * chunkSize))
-                    } catch (e) {
-                        this.logger.error('protocol error', e)
-                        this.activeSession.abort()
-                        this.activeSession = null
-                        terminal.enablePassthrough = true
-                        return
-                    }
-                }
+            this.attachToSession(sentry, terminal)
+            this.subscribeUntilDetached(terminal, terminal.sessionChanged$.subscribe(() => {
+                this.attachToSession(sentry, terminal)
             }))
         })
     }
 
+    private attachToSession (sentry, terminal) {
+        if (!terminal.session) {
+            return
+        }
+        this.subscribeUntilDetached(terminal, terminal.session.binaryOutput$.subscribe(data => {
+            const chunkSize = 1024
+            console.log('z rx', data.toString(), data)
+            for (let i = 0; i <= Math.floor(data.length / chunkSize); i++) {
+                try {
+                    sentry.consume(Buffer.from(data.slice(i * chunkSize, (i + 1) * chunkSize)))
+                } catch (e) {
+                    this.showMessage(terminal, colors.bgRed.black(' Error ') + ' ' + e)
+                    this.logger.error('protocol error', e)
+                    this.activeSession.abort()
+                    this.activeSession = null
+                    terminal.enablePassthrough = true
+                    return
+                }
+            }
+        }))
+    }
+
     private async process (terminal, detection): Promise<void> {
         this.showMessage(terminal, colors.bgBlue.black(' ZMODEM ') + ' Session started')
         this.showMessage(terminal, '------------------------')