diff --git a/src/serial.rs b/src/serial.rs
index 817fb67..79c6b12 100644
--- a/src/serial.rs
+++ b/src/serial.rs
@@ -101,6 +101,8 @@ impl<UART: serial::Uart> SerialIO<UART> {
             .take_while(|c| *c != '\n')
             .collect();
 
+        // TODO: \r\n is true for sim800l, but might not be valud for other devices. Re-implement
+        // this function so that it can be used on all devices.
         // \r must come right before \n on read; take_while excludes the matched element.
         if line.ends_with('\r') {
             line.push('\n');