diff --git a/src/language-html/index.js b/src/language-html/index.js
index e90f51a21..f8a819ae4 100644
--- a/src/language-html/index.js
+++ b/src/language-html/index.js
@@ -21,6 +21,11 @@ const languages = [
       since: "1.15.0",
       parsers: ["html"],
       vscodeLanguageIds: ["html"]
+    },
+    extend: {
+      extensions: [
+        ".mjml" // MJML is considered XML in Linguist but it should be formatted as HTML
+      ]
     }
   }),
   createLanguage(require("linguist-languages/data/vue"), {
diff --git a/tests/html_mjml/__snapshots__/jsfmt.spec.js.snap b/tests/html_mjml/__snapshots__/jsfmt.spec.js.snap
new file mode 100644
index 000000000..57c550ef8
--- /dev/null
+++ b/tests/html_mjml/__snapshots__/jsfmt.spec.js.snap
@@ -0,0 +1,65 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`empty.mjml 1`] = `
+====================================options=====================================
+parsers: ["html"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<mjml></mjml>
+=====================================output=====================================
+<mjml></mjml>
+
+================================================================================
+`;
+
+exports[`head.mjml 1`] = `
+====================================options=====================================
+parsers: ["html"]
+printWidth: 80
+                                                                                | printWidth
+=====================================input======================================
+<mjml>
+  <mj-head>
+    <mj-title>
+    
+    
+    The green fix eats mango.
+    
+    
+    </mj-title>
+    <mj-breakpoint width="600px" />
+    <mj-preview>Do 
+    
+    you like cheese? We do!</mj-preview>
+    <mj-attributes>
+      <mj-text 
+      
+      
+      
+      align="left" color="#000"
+      
+      
+         font-family="-apple-system,BlinkMacSystemFont,Helvetica,sans-serif" />
+    </mj-attributes>
+  </mj-head>
+</mjml>
+
+=====================================output=====================================
+<mjml>
+  <mj-head>
+    <mj-title> The green fix eats mango. </mj-title>
+    <mj-breakpoint width="600px" />
+    <mj-preview>Do you like cheese? We do!</mj-preview>
+    <mj-attributes>
+      <mj-text
+        align="left"
+        color="#000"
+        font-family="-apple-system,BlinkMacSystemFont,Helvetica,sans-serif"
+      />
+    </mj-attributes>
+  </mj-head>
+</mjml>
+
+================================================================================
+`;
diff --git a/tests/html_mjml/empty.mjml b/tests/html_mjml/empty.mjml
new file mode 100644
index 000000000..27a34a57c
--- /dev/null
+++ b/tests/html_mjml/empty.mjml
@@ -0,0 +1 @@
+<mjml></mjml>
\ No newline at end of file
diff --git a/tests/html_mjml/head.mjml b/tests/html_mjml/head.mjml
new file mode 100644
index 000000000..477716530
--- /dev/null
+++ b/tests/html_mjml/head.mjml
@@ -0,0 +1,25 @@
+<mjml>
+  <mj-head>
+    <mj-title>
+    
+    
+    The green fix eats mango.
+    
+    
+    </mj-title>
+    <mj-breakpoint width="600px" />
+    <mj-preview>Do 
+    
+    you like cheese? We do!</mj-preview>
+    <mj-attributes>
+      <mj-text 
+      
+      
+      
+      align="left" color="#000"
+      
+      
+         font-family="-apple-system,BlinkMacSystemFont,Helvetica,sans-serif" />
+    </mj-attributes>
+  </mj-head>
+</mjml>
diff --git a/tests/html_mjml/jsfmt.spec.js b/tests/html_mjml/jsfmt.spec.js
new file mode 100644
index 000000000..53763df9b
--- /dev/null
+++ b/tests/html_mjml/jsfmt.spec.js
@@ -0,0 +1 @@
+run_spec(__dirname, ["html"]);
diff --git a/tests_integration/__tests__/__snapshots__/support-info.js.snap b/tests_integration/__tests__/__snapshots__/support-info.js.snap
index afa4ed067..7c444ae28 100644
--- a/tests_integration/__tests__/__snapshots__/support-info.js.snap
+++ b/tests_integration/__tests__/__snapshots__/support-info.js.snap
@@ -906,7 +906,8 @@ exports[`CLI --support-info (stdout) 1`] = `
         \\".inc\\",
         \\".st\\",
         \\".xht\\",
-        \\".xhtml\\"
+        \\".xhtml\\",
+        \\".mjml\\"
       ],
       \\"linguistLanguageId\\": 146,
       \\"name\\": \\"HTML\\",