diff --git a/src/descriptor.js b/src/descriptor.js
index 69a6034b..af341487 100644
--- a/src/descriptor.js
+++ b/src/descriptor.js
@@ -1394,9 +1394,14 @@ function createDeserialize(
                                 ),
                                 ts.factory.createCallExpression(
                                     ts.factory.createPropertyAccessExpression(
-                                        ts.factory.createPropertyAccessExpression(
-                                            pbIdentifier,
-                                            "Map"
+                                        ts.factory.createParenthesizedExpression(
+                                            ts.factory.createAsExpression(
+                                                ts.factory.createPropertyAccessExpression(
+                                                    pbIdentifier,
+                                                    "Map"
+                                                ),
+                                                ts.factory.createToken(ts.SyntaxKind.AnyKeyword)
+                                            ),
                                         ),
                                         "deserializeBinary"
                                     ),
@@ -1806,4 +1811,4 @@ function processDescriptorRecursively(
     return statements;
 }
 
-module.exports = { processDescriptorRecursively, createEnum, createNamespace }
\ No newline at end of file
+module.exports = { processDescriptorRecursively, createEnum, createNamespace }