diff --git a/example/natspec_contract.html b/example/natspec_contract.html
index 94edda68d..8d12b4a81 100644
--- a/example/natspec_contract.html
+++ b/example/natspec_contract.html
@@ -68,7 +68,8 @@
         <button type="button" onClick="createExampleContract();">create example contract</button>
     </div>
     <div id='call' style='visibility: hidden;'>
-        <input type="number" id="value" onkeyup='callExampleContract()'></input>
+        <input type="number" id="value"></input>
+		<button type="button" onClick="callExampleContract()">Call Contract</button>
     </div>
     <div id="result"></div>
 </body>