diff --git a/src/machine/serial-rtt.go b/src/machine/serial-rtt.go
index 62c3eb9e8..15f6463de 100644
--- a/src/machine/serial-rtt.go
+++ b/src/machine/serial-rtt.go
@@ -123,6 +123,12 @@ func (b *rttBuffer) buffered() int {
 	return int((writeOffset - readOffset) % rttBufferSizeDown)
 }
 
+// Write a single byte to the RTT output buffer.
+//
+// This method is set to not be inlined, to avoid blowing up binary size as a
+// result of inlining writeByte everywhere a println exists.
+//
+//go:noinline
 func (s *rttSerial) WriteByte(b byte) error {
 	s.buffersUp[0].writeByte(b)
 	return nil