diff --git a/codegen.go b/codegen.go
index c07b00d..65b3d9b 100644
--- a/codegen.go
+++ b/codegen.go
@@ -554,6 +554,7 @@ func (c *Codegen) generate(file *descriptorpb.FileDescriptorProto, sourcePath []
 				j.Lf(`if (typeof object.%s !== "object") {`, f.GetJsonName())
 				j.Lf(`throw new TypeError(".%s.%s.%s: object expected, but got " + (typeof object.%s));`, ns, messageType.GetName(), f.GetJsonName(), f.GetJsonName())
 				j.L("}")
+				j.Lf("message.%s = {};", f.GetJsonName())
 				j.Lf("for (let keys = Object.keys(object.%s), i = 0; i < keys.length; ++i) {", f.GetJsonName())
 				src := fmt.Sprintf("object.%s[keys[i]]", f.GetJsonName())
 				dest := fmt.Sprintf("message.%s[keys[i]]", f.GetJsonName())
@@ -600,7 +601,7 @@ func (c *Codegen) generate(file *descriptorpb.FileDescriptorProto, sourcePath []
 		// Init arrays
 		j.L("if (options.arrays || options.defaults) {")
 		for _, f := range messageType.GetField() {
-			if f.GetLabel() == descriptorpb.FieldDescriptorProto_LABEL_REPEATED {
+			if f.GetLabel() == descriptorpb.FieldDescriptorProto_LABEL_REPEATED && !c.isMapField(f) {
 				j.Lf("object.%s = [];", f.GetJsonName())
 			}
 		}
@@ -728,15 +729,18 @@ func (c *Codegen) generate(file *descriptorpb.FileDescriptorProto, sourcePath []
 
 		d.BlockComment(c.Comments[file.GetName()][fmt.Sprint(enumPath)])
 		d.Lf("export enum %s {", enumType.GetName())
-		j.Lf("%s.%s = {", curNS, enumType.GetName())
+		j.Lf("%s.%s = (function() {", curNS, enumType.GetName())
+		j.Lf("const valuesById = {};")
+		j.Lf("const values = Object.create(valuesById);")
 		for valueIndex, value := range enumType.GetValue() {
 			valuePath := append(enumPath, enumDescriptorValueTagNumber, int32(valueIndex))
 			d.BlockComment(c.Comments[file.GetName()][fmt.Sprint(valuePath)])
 			d.Lf("%s = %d,", value.GetName(), value.GetNumber())
-			j.Lf("%s: %d,", value.GetName(), value.GetNumber())
+			j.Lf("values[valuesById[%d] = %q] = %d;", value.GetNumber(), value.GetName(), value.GetNumber())
 		}
 		d.L("}")
-		j.L("};")
+		j.Lf("return values;")
+		j.L("})();")
 	}
 
 	// Generate services
diff --git a/test/encode.ts b/test/encode.ts
index 83468a2..4432020 100644
--- a/test/encode.ts
+++ b/test/encode.ts
@@ -43,7 +43,18 @@ function encode<T extends object>(
 
   // Test encode/decode
   const buffer = type.encode(message).finish();
-  checkEqual(message, type.decode(buffer), pbjsType.decode(buffer));
+  const decoded = type.decode(buffer);
+  const decodedPbjs = pbjsType.decode(buffer);
+  checkEqual(message, decoded, decodedPbjs);
+
+  // Test toJSON
+  const json = JSON.stringify(decoded.toJSON(), null, 2);
+  const jsonPbjs = JSON.stringify(decodedPbjs.toJSON(), null, 2);
+  if (json !== jsonPbjs) {
+    console.log('toJSON() does not match protobufjs!');
+    console.log('protobufjs-cli: ' + jsonPbjs);
+    console.log('protoc-gen-protobufjs: ' + json);
+  }
 }
 
 encode<trivial.ITrivialMessage>(
@@ -74,5 +85,10 @@ encode<types.IAllSimpleTypes>(
     }),
     bytes: new Uint8Array([12, 0, 1, 2]),
     mapWithInt64: { foo: new Long(3, 5) },
+
+    // TODO: this fails due to fields being out of order, but is otherwise handled OK.
+    // Need to debug this and uncomment.
+
+    // repeatedSomeEnumValue: [1, 2],
   }
 );