diff --git a/web/app.js b/web/app.js
index 5de60a5..0d7f8ff 100644
--- a/web/app.js
+++ b/web/app.js
@@ -477,8 +477,8 @@ function updateStatusLine() {
 // Stirrer: whenever not running. Checkbox: whenever not running.
 function updateControlsEnabled() {
 	const sudRunning = RUNNING_STATES.has(sudState);
-	document.getElementById('temp-soll').disabled = !closedLoop;
-	document.getElementById('heatrate-soll').disabled = !closedLoop;
+	document.getElementById('temp-soll').disabled = !(closedLoop && !sudRunning);
+	document.getElementById('heatrate-soll').disabled = !(closedLoop && !sudRunning);
 	document.getElementById('heater-power').disabled = !(!closedLoop && !sudRunning);
 	document.getElementById('stirrer-speed').disabled = sudRunning;
 	document.getElementById('closed-loop').disabled = sudRunning;