diff --git a/src/subParsers/makehtml/githubCodeBlocks.js b/src/subParsers/makehtml/githubCodeBlocks.js
index 2976b497..f29ec955 100644
--- a/src/subParsers/makehtml/githubCodeBlocks.js
+++ b/src/subParsers/makehtml/githubCodeBlocks.js
@@ -20,7 +20,7 @@ showdown.subParser('makehtml.githubCodeBlocks', function (text, options, globals
 
   text += '¨0';
 
-  text = text.replace(/(?:^|\n)(```+|~~~+)(?: *)([^\s`~]*)\n([\s\S]*?)\n\1/g, function (wholeMatch, delim, language, codeblock) {
+  text = text.replace(/(?:^|\n)(?: {0,3})(```+|~~~+)(?: *)([^\s`~]*)\n([\s\S]*?)\n(?: {0,3})\1/g, function (wholeMatch, delim, language, codeblock) {
     var end = (options.omitExtraWLInCodeBlocks) ? '' : '\n';
 
     // First parse the github code block
diff --git a/test/functional/makehtml/cases/issues/#523.leading-space-breaks-gfm-code-blocks.html b/test/functional/makehtml/cases/issues/#523.leading-space-breaks-gfm-code-blocks.html
new file mode 100644
index 00000000..ab9ddaa3
--- /dev/null
+++ b/test/functional/makehtml/cases/issues/#523.leading-space-breaks-gfm-code-blocks.html
@@ -0,0 +1,15 @@
+<pre><code class="javascript language-javascript">var test = test;
+function foo() {
+  return 'bar';
+}
+</code></pre>
+<pre><code class="javascript language-javascript">var test = test;
+function foo() {
+  return 'bar';
+}
+</code></pre>
+<pre><code class="javascript language-javascript">var test = test;
+function foo() {
+  return 'bar';
+}
+</code></pre>
diff --git a/test/functional/makehtml/cases/issues/#523.leading-space-breaks-gfm-code-blocks.md b/test/functional/makehtml/cases/issues/#523.leading-space-breaks-gfm-code-blocks.md
new file mode 100644
index 00000000..9289cd06
--- /dev/null
+++ b/test/functional/makehtml/cases/issues/#523.leading-space-breaks-gfm-code-blocks.md
@@ -0,0 +1,20 @@
+ ```javascript
+var test = test;
+function foo() {
+  return 'bar';
+}
+ ```
+
+  ```javascript
+var test = test;
+function foo() {
+  return 'bar';
+}
+  ```
+
+   ```javascript
+var test = test;
+function foo() {
+  return 'bar';
+}
+   ```