diff --git a/tests/wpt/web-platform-tests/common/form-submission.py b/tests/wpt/web-platform-tests/common/form-submission.py
index eb9c654444b..78f96fe3145 100644
--- a/tests/wpt/web-platform-tests/common/form-submission.py
+++ b/tests/wpt/web-platform-tests/common/form-submission.py
@@ -4,6 +4,11 @@ def main(request, response):
             return 'OK'
         else:
             return 'FAIL'
+    elif request.headers.get('Content-Type') == 'text/plain':
+        if request.body == 'qux=baz\r\n':
+            return 'OK'
+        else:
+            return 'FAIL'
     else:
         if request.POST.first('foo') == 'bar':
             return 'OK'
diff --git a/tests/wpt/web-platform-tests/html/semantics/forms/form-submission-0/submit-entity-body.html b/tests/wpt/web-platform-tests/html/semantics/forms/form-submission-0/submit-entity-body.html
index 3c6e0b725c2..736ef1318b1 100644
--- a/tests/wpt/web-platform-tests/html/semantics/forms/form-submission-0/submit-entity-body.html
+++ b/tests/wpt/web-platform-tests/html/semantics/forms/form-submission-0/submit-entity-body.html
@@ -18,6 +18,13 @@ var simple_tests = [
     submitelement: "",
     submitaction: function(doc) { doc.getElementById("testform").submit(); }
   },
+  {
+    name: "form submission from form should navigate to url with text/plain",
+    input: "<textarea name=qux>baz</textarea>",
+    enctype: "text/plain",
+    submitelement: "",
+    submitaction: function(doc) { doc.getElementById("testform").submit(); }
+  },
   {
     name: "form submission from button should navigate to url with x-www-form-urlencoded",
     input: "<input name=foo value=bara>",
@@ -32,6 +39,13 @@ var simple_tests = [
     submitelement: "<button id=buttonsubmit type=\"submit\">Submit</button>",
     submitaction: function(doc) { doc.getElementById("buttonsubmit").click(); }
   },
+  {
+    name: "form submission from button should navigate to url with text/plain",
+    input: "<textarea name=qux>baz</textarea>",
+    enctype: "text/plain",
+    submitelement: "<button id=buttonsubmit type=\"submit\">Submit</button>",
+    submitaction: function(doc) { doc.getElementById("buttonsubmit").click(); }
+  },
   {
     name: "form submission from input should navigate to url with x-www-form-urlencoded",
     input: "<input name=foo value=bara>",
@@ -46,6 +60,13 @@ var simple_tests = [
     submitelement: "<input id=inputsubmit type=\"submit\">Submit</input>",
     submitaction: function(doc) { doc.getElementById("inputsubmit").click(); }
   },
+  {
+    name: "form submission from input should navigate to url with text/plain",
+    input: "<input name=qux value=baz>",
+    enctype: "text/plain",
+    submitelement: "<input id=inputsubmit type=\"submit\">Submit</input>",
+    submitaction: function(doc) { doc.getElementById("inputsubmit").click(); }
+  }
 ];
 simple_tests.forEach(function(test_obj) {
   test_obj.test = async_test(test_obj.name);