diff --git a/src/enum.js b/src/enum.js
index c847fceda..cc797a68e 100644
--- a/src/enum.js
+++ b/src/enum.js
@@ -94,8 +94,8 @@ EnumPrototype.add = function(name, id) {
     if (!util.isString(name))
         throw TypeError("name must be a string");
     /* istanbul ignore next */
-    if (!util.isInteger(id) || id < 0)
-        throw TypeError("id must be a non-negative integer");
+    if (!util.isInteger(id))
+        throw TypeError("id must be an integer");
     /* istanbul ignore next */
     if (this.values[name] !== undefined)
         throw Error("duplicate name '" + name + "' in " + this);
diff --git a/src/root.js b/src/root.js
index 7d19f4b1e..dbedb805f 100644
--- a/src/root.js
+++ b/src/root.js
@@ -88,6 +88,8 @@ RootPrototype.load = function load(filename, options, callback) {
     var self = this;
     if (!callback)
         return util.asPromise(load, self, filename);
+    
+    var sync = callback === SYNC; // undocumented
 
     // Finishes loading by calling the callback (exactly once)
     function finish(err, root) {
@@ -98,8 +100,6 @@ RootPrototype.load = function load(filename, options, callback) {
         cb(err, root);
     }
 
-    var sync = callback === SYNC; // undocumented
-
     // Processes a single file
     function process(filename, source) {
         try {
@@ -120,6 +120,8 @@ RootPrototype.load = function load(filename, options, callback) {
                     });
             }
         } catch (err) {
+            if (sync)
+                throw err;
             finish(err);
             return;
         }