diff --git a/packages/mdx/test/index.test.js b/packages/mdx/test/index.test.js
index 3ae6b089a..db265b47d 100644
--- a/packages/mdx/test/index.test.js
+++ b/packages/mdx/test/index.test.js
@@ -171,7 +171,7 @@ COPY start.sh /home/start.sh
   )
 })
 
-it.skip('Should support comments', async () => {
+it('Should support comments', async () => {
   const result = await mdx(`
 <!-- a Markdown comment -->
 A paragraph
diff --git a/packages/remark-mdx/index.js b/packages/remark-mdx/index.js
index 9ad335a4a..3d4185aec 100644
--- a/packages/remark-mdx/index.js
+++ b/packages/remark-mdx/index.js
@@ -9,6 +9,7 @@ const EMPTY_NEWLINE = '\n\n'
 const LESS_THAN = '<'
 const GREATER_THAN = '>'
 const SLASH = '/'
+const EXCLAMATION = '!'
 
 const isImport = text => IMPORT_REGEX.test(text)
 const isExport = text => EXPORT_REGEX.test(text)
@@ -69,6 +70,7 @@ function attachParser(parser) {
     if (
       nextChar !== GREATER_THAN &&
       nextChar !== SLASH &&
+      nextChar !== EXCLAMATION &&
       !isAlphabetical(nextChar)
     ) {
       return