diff --git a/adafruit_esp32spi/adafruit_esp32spi_socket.py b/adafruit_esp32spi/adafruit_esp32spi_socket.py
index 1cf379f..fa3a082 100644
--- a/adafruit_esp32spi/adafruit_esp32spi_socket.py
+++ b/adafruit_esp32spi/adafruit_esp32spi_socket.py
@@ -121,7 +121,7 @@ def recv_into(self, buffer, nbytes: int = 0):
                 )
                 buffer[num_read : num_read + len(bytes_read)] = bytes_read
                 num_read += len(bytes_read)
-                num_to_read -= num_read
+                num_to_read -= len(bytes_read)
             elif num_read > 0:
                 # We got a message, but there are no more bytes to read, so we can stop.
                 break