diff --git a/repos/os/src/server/vmm/spec/arm_v8/pl011.cc b/repos/os/src/server/vmm/spec/arm_v8/pl011.cc
index e9903fd51..a9cd8f834 100644
--- a/repos/os/src/server/vmm/spec/arm_v8/pl011.cc
+++ b/repos/os/src/server/vmm/spec/arm_v8/pl011.cc
@@ -64,7 +64,7 @@ void Pl011::_read()
 {
 	if (!_terminal.avail()) return;
 
-	while (_terminal.avail()) {
+	while (_terminal.avail() && _rx_buf.avail_capacity()) {
 		unsigned char c = 0;
 		_terminal.read(&c, 1);
 		_rx_buf.add(c);