diff --git a/octokit.coffee b/octokit.coffee
index 972615a6..dc6d82fb 100644
--- a/octokit.coffee
+++ b/octokit.coffee
@@ -791,15 +791,17 @@ makeOctokit = (newPromise, allPromises, XMLHttpRequest, base64encode, userAgent)
           # Post a new blob object, getting a blob SHA back
           # -------
           @postBlob = (content, isBase64) ->
-            if typeof (content) is 'string'
-              # Base64 encode the content if it is binary (isBase64)
-              content = base64encode(content) if isBase64
-
+            if isBase64
               content =
-                content: content
-                encoding: 'utf-8'
-
-            content.encoding = 'base64' if isBase64
+                content: content,
+                encoding: 'base64'
+            else
+              if typeof (content) is 'string'
+                # Base64 encode the content if it is binary (isBase64)
+                content = base64encode(content) if isBase64
+                content =
+                  content: content
+                  encoding: 'utf-8'
 
             _request('POST', "#{_repoPath}/git/blobs", content)
             .then (res) =>
diff --git a/octokit.js b/octokit.js
index 3d033435..ed09ce42 100644
--- a/octokit.js
+++ b/octokit.js
@@ -776,17 +776,21 @@
             };
             this.postBlob = function(content, isBase64) {
               var _this = this;
-              if (typeof content === 'string') {
-                if (isBase64) {
-                  content = base64encode(content);
-                }
+              if (isBase64) {
                 content = {
                   content: content,
-                  encoding: 'utf-8'
+                  encoding: 'base64'
                 };
-              }
-              if (isBase64) {
-                content.encoding = 'base64';
+              } else {
+                if (typeof content === 'string') {
+                  if (isBase64) {
+                    content = base64encode(content);
+                  }
+                  content = {
+                    content: content,
+                    encoding: 'utf-8'
+                  };
+                }
               }
               return _request('POST', "" + _repoPath + "/git/blobs", content).then(function(res) {
                 return res.sha;