diff --git a/docs/library/pyb.I2C.rst b/docs/library/pyb.I2C.rst
index 1eb426168c..e40684a78a 100644
--- a/docs/library/pyb.I2C.rst
+++ b/docs/library/pyb.I2C.rst
@@ -91,7 +91,7 @@ Methods
 
    Read from the memory of an I2C device:
    
-     - ``data`` can be an integer or a buffer to read into
+     - ``data`` can be an integer (number of bytes to read) or a buffer to read into
      - ``addr`` is the I2C device address
      - ``memaddr`` is the memory location within the I2C device
      - ``timeout`` is the timeout in milliseconds to wait for the read