diff --git a/javascript/edit-attention.js b/javascript/edit-attention.js
index 79566a2e2..3f1d2fbbd 100644
--- a/javascript/edit-attention.js
+++ b/javascript/edit-attention.js
@@ -25,6 +25,7 @@ addEventListener('keydown', (event) => {
 	} else {
 		end = target.value.slice(selectionEnd + 1).indexOf(")") + 1;
 		weight = parseFloat(target.value.slice(selectionEnd + 1, selectionEnd + 1 + end));
+		if (isNaN(weight)) return;
 		if (event.key == minus) weight -= 0.1;
 		if (event.key == plus) weight += 0.1;