diff --git a/lib/definitions.js b/lib/definitions.js
index 81a4ac8..e887f7d 100644
--- a/lib/definitions.js
+++ b/lib/definitions.js
@@ -37,7 +37,7 @@ class Definitions {
                         self.components[json.name] = json;
 
                         if (json.extensions) {
-                            var extensions = [];
+                            var extensions = {};
 
                             for (var key in json.extensions) {
                                 extensions[json.extensions[key].id] = json.extensions[key];
@@ -176,15 +176,13 @@ class Definitions {
             if (this.components[fieldType].extensions !== undefined) {
 
                 if (decoded.id !== undefined) {
-                    var extensionDef = this.components[fieldType].extensions.find(function(extension) {
-                        if (extension) {
-                            return extension.id == decoded.id;
-                        } else {
-                            return 0;
-                        }
-                    });
-
-                    if (extensionDef) {
+                    var extensions = this.components[fieldType].extensions;
+                    var extensionDef = false;
+                    for(var extensionId in extensions) {
+                        if(extensionId == decoded.id) 
+                            extensionDef = extensions[extensionId];
+                    }
+                    if (extensionDef != false) {
                         decoded.payload = this.decode_fields(reader, extensionDef.fields);
                     } else {
                         console.warn('Error: Extensions of field type ' + fieldType + ' with id ' + decoded.id + ' is missing. (' + field.name + ').');