diff --git a/lib/src/base_client.dart b/lib/src/base_client.dart
index ff5b23d94b..204393d638 100644
--- a/lib/src/base_client.dart
+++ b/lib/src/base_client.dart
@@ -152,8 +152,14 @@ abstract class BaseClient implements Client {
     if (url is String) url = Uri.parse(url);
     var request = Request(method, url);
 
-    if (headers != null) request.headers.addAll(headers);
-    if (encoding != null) request.encoding = encoding;
+    if (headers != null) {
+      request.headers.addAll(headers);
+    }
+    if (encoding != null) {
+      request.encoding = encoding;
+    } else {
+      request.isIgnoreEncoding = true;
+    }
     if (body != null) {
       if (body is String) {
         request.body = body;
diff --git a/lib/src/request.dart b/lib/src/request.dart
index f18959d8b2..069e393953 100644
--- a/lib/src/request.dart
+++ b/lib/src/request.dart
@@ -13,6 +13,8 @@ import 'utils.dart';
 
 /// An HTTP request where the entire request body is known in advance.
 class Request extends BaseRequest {
+  bool isIgnoreEncoding = false;
+
   /// The size of the request body, in bytes. This is calculated from
   /// [bodyBytes].
   ///
@@ -56,7 +58,11 @@ class Request extends BaseRequest {
     _defaultEncoding = value;
     var contentType = _contentType;
     if (contentType == null) return;
-    _contentType = contentType.change(parameters: {'charset': value.name});
+    if (isIgnoreEncoding) {
+      _contentType = contentType.change(parameters: {});
+    } else {
+      _contentType = contentType.change(parameters: {'charset': value.name});
+    }
   }
 
   // TODO(nweiz): make this return a read-only view
@@ -85,8 +91,9 @@ class Request extends BaseRequest {
     bodyBytes = encoding.encode(value);
     var contentType = _contentType;
     if (contentType == null) {
-      _contentType = MediaType("text", "plain", {'charset': encoding.name});
-    } else if (!contentType.parameters.containsKey('charset')) {
+      _contentType = new MediaType("text", "plain", {'charset': encoding.name});
+    } else if (!contentType.parameters.containsKey('charset') &&
+        !isIgnoreEncoding) {
       _contentType = contentType.change(parameters: {'charset': encoding.name});
     }
   }