diff --git a/src/encoder.js b/src/encoder.js
index 898a43b8c..cf6c9a916 100644
--- a/src/encoder.js
+++ b/src/encoder.js
@@ -22,17 +22,6 @@ function genTypePartial(gen, field, fieldIndex, ref) {
         : gen("types[%d].encode(%s,w.uint32(%d).fork()).ldelim()", fieldIndex, ref, (field.id << 3 | 2) >>> 0);
 }
 
-/**
- * Compares reflected fields by id.
- * @param {Field} a First field
- * @param {Field} b Second field
- * @returns {number} Comparison value
- * @ignore
- */
-function compareFieldsById(a, b) {
-    return a.id - b.id;
-}
-
 /**
  * Generates an encoder specific to the specified message type.
  * @param {Type} mtype Message type
@@ -51,7 +40,7 @@ function encoder(mtype) {
     var fields = /* initializes */ mtype.fieldsArray;
     /* istanbul ignore else */
     if (encoder.compat)
-        fields = fields.slice().sort(compareFieldsById);
+        fields = fields.slice().sort(util.compareFieldsById);
 
     for (var i = 0; i < fields.length; ++i) {
         var field    = fields[i].resolve(),
diff --git a/src/util.js b/src/util.js
index 3a255da6f..9e3557e3c 100644
--- a/src/util.js
+++ b/src/util.js
@@ -49,3 +49,13 @@ util.safeProp = function safeProp(prop) {
 util.ucFirst = function ucFirst(str) {
     return str.charAt(0).toUpperCase() + str.substring(1);
 };
+
+/**
+ * Compares reflected fields by id.
+ * @param {Field} a First field
+ * @param {Field} b Second field
+ * @returns {number} Comparison value
+ */
+util.compareFieldsById = function compareFieldsById(a, b) {
+    return a.id - b.id;
+};