diff --git a/js/usercss.js b/js/usercss.js
index 54d41526..720ac3fb 100644
--- a/js/usercss.js
+++ b/js/usercss.js
@@ -226,7 +226,7 @@ var usercss = (() => {
           result.default = range[0];
           result.min = range[1];
           result.max = range[2];
-          result.step = range[3] || 1;
+          result.step = range[3] == 0 ? 1 : range[3];
         }
         break;
       }
diff --git a/manage/config-dialog.js b/manage/config-dialog.js
index 2e2f0988..d749fada 100644
--- a/manage/config-dialog.js
+++ b/manage/config-dialog.js
@@ -317,8 +317,8 @@ function configDialog(style) {
 
   // Clamp input[type=number] to a valid range
   function clampValue(value, va) {
-    const min = va.min || 0;
-    const max = va.max || 100;
+    const min = typeof va.min === 'undefined' ? 0 : va.min;
+    const max = typeof va.max === 'undefined' ? 100 : va.max;
     if (value < min) {
       return min;
     }