diff --git a/macrovision.html b/macrovision.html
index 8a03cd10..2216c55e 100644
--- a/macrovision.html
+++ b/macrovision.html
@@ -25,7 +25,7 @@
   <div id="main-area">
     <div id="options">
       <div class="option-row">
-        <input type="number" id="options-height-value" value="10">
+        <input type="number" id="options-height-value" min="1" value="10">
         <select id="options-height-unit">
           <option>meters</option>
           <option>kilometers</option>
diff --git a/macrovision.js b/macrovision.js
index a19603d5..fcd2c38a 100644
--- a/macrovision.js
+++ b/macrovision.js
@@ -264,7 +264,7 @@ document.addEventListener("mousemove", (e) => {
 });
 
 function updateWorldHeight() {
-    const value = document.querySelector("#options-height-value").value;
+    const value = Math.max(1, document.querySelector("#options-height-value").value);
     const unit = document.querySelector("#options-height-unit").value;
     const oldHeight = config.height;