diff --git a/lib/compiler.js b/lib/compiler.js
index 5913ca631..7a98aac14 100644
--- a/lib/compiler.js
+++ b/lib/compiler.js
@@ -69,6 +69,14 @@ Compiler.prototype.compile_serpent = function(contractFile) {
   json = JSON.parse(result.output.trim());
   className = contractFile.split('.')[0].split("/").pop();
 
+  for (var i=0; i < json.length; i++) {
+    var elem = json[i];
+
+    if (elem.outputs.length > 0) {
+      elem.constant = true;
+    }
+  }
+
   compiled_object = {}
   compiled_object[className] = {};
   compiled_object[className].code = code.trim();