diff --git a/calc.html b/calc.html
index a4a1b95e..bf2d39ef 100644
--- a/calc.html
+++ b/calc.html
@@ -254,7 +254,7 @@
 
         <tr>
         <td class="setting-label">Mining productivity bonus:</td>
-        <td>+<input id="mprod" class="mprod" type="number" step="2" value="0" min="0" onchange="changeMprod()">%</td>
+        <td>+<input id="mprod" class="mprod" type="number" step="10" value="0" min="0" onchange="changeMprod()">%</td>
         </tr>
 
         <tr>