diff --git a/main.js b/main.js
index a1985ad..2dcdd25 100644
--- a/main.js
+++ b/main.js
@@ -46,6 +46,7 @@ function evaluate() {
 	worker.postMessage({command: "compute", queue, m});
 	timeoutId = setTimeout(() => {
 		document.querySelector("#result").value = "calculating...";
+		switchInputs(false);
 		switchButtons(false);
 	}, 500);
 }
@@ -115,17 +116,24 @@ function switchButtons(enabled) {
 	}
 }
 
+function switchInputs(enabled) {
+	document.querySelector("#expr").disabled = !enabled;
+	document.querySelector("#modulus").disabled = !enabled;
+}
+
 let timeoutId = null;
 const worker = new Worker("./workers/compute.js");
 worker.addEventListener("message", (message) => {
 	clearTimeout(timeoutId);
 	document.querySelector("#result").value = message.data;
+	switchInputs(true);
 	switchButtons(true);
 });
 worker.addEventListener("error", (e) => {
 	console.log(e);
 	clearTimeout(timeoutId);
 	document.querySelector("#result").value = e.message;
+	switchInputs(true);
 	switchButtons(true);
 });