diff --git a/index.html b/index.html
index db33a3b..93409dd 100644
--- a/index.html
+++ b/index.html
@@ -139981,8 +139981,19 @@ <h4>
             try {
 
 
-                let n = parseInt($("#share-threshold")[0].value);
-                let m = parseInt($("#share-total")[0].value);
+                let thresholdValue = $("#share-threshold")[0].value.trim();
+                let totalValue = $("#share-total")[0].value.trim();
+                if (!/^\d+$/.test(thresholdValue) || !/^\d+$/.test(totalValue)) {
+                    await run_task(type_text, "#calc-status", "Threshold and total shares must be whole numbers", "text-red");
+                    return;
+                }
+
+                let n = parseInt(thresholdValue, 10);
+                let m = parseInt(totalValue, 10);
+                if (n < 2) {
+                    await run_task(type_text, "#calc-status", "Minimum threshold is 2 shares", "text-red");
+                    return;
+                }
                 if (m > 15) {
                     await run_task(type_text, "#calc-status", "This tool limited to 15 total shares", "text-red");
                     return;
@@ -140302,4 +140313,4 @@ <h4>
 
 
 
-</body></html>
\ No newline at end of file
+</body></html>