diff --git a/wagtail/wagtailcore/blocks/field_block.py b/wagtail/wagtailcore/blocks/field_block.py
index ddc740a21..4e953702b 100644
--- a/wagtail/wagtailcore/blocks/field_block.py
+++ b/wagtail/wagtailcore/blocks/field_block.py
@@ -261,8 +261,23 @@ class RawHTMLBlock(FieldBlock):
             widget=forms.Textarea)
         super(RawHTMLBlock, self).__init__(**kwargs)
 
-    def render_basic(self, value):
-        return mark_safe(value)  # if it isn't safe, that's the site admin's problem for allowing raw HTML blocks in the first place...
+    def get_default(self):
+        return mark_safe(self.meta.default or '')
+
+    def to_python(self, value):
+        return mark_safe(value)
+
+    def get_prep_value(self, value):
+        # explicitly convert to a plain string, just in case we're using some serialisation method
+        # that doesn't cope with SafeText values correctly
+        return str(value)
+
+    def value_for_form(self, value):
+        # need to explicitly mark as unsafe, or it'll output unescaped HTML in the textarea
+        return str(value)
+
+    def value_from_form(self, value):
+        return mark_safe(value)
 
     class Meta:
         icon = 'code'
diff --git a/wagtail/wagtailcore/tests/test_blocks.py b/wagtail/wagtailcore/tests/test_blocks.py
index a4d38ce2e..7f4524d95 100644
--- a/wagtail/wagtailcore/tests/test_blocks.py
+++ b/wagtail/wagtailcore/tests/test_blocks.py
@@ -4,6 +4,7 @@ from django import forms
 from django.forms.utils import ErrorList
 from django.core.exceptions import ValidationError
 from django.test import TestCase
+from django.utils.safestring import mark_safe, SafeText
 
 from wagtail.wagtailcore import blocks
 from wagtail.wagtailcore.models import Page
@@ -267,6 +268,77 @@ class TestChoiceBlock(unittest.TestCase):
         )
 
 
+class TestRawHTMLBlock(unittest.TestCase):
+    def test_get_default_with_fallback_value(self):
+        default_value = blocks.RawHTMLBlock().get_default()
+        self.assertEqual(default_value, '')
+        self.assertTrue(isinstance(default_value, SafeText))
+
+    def test_get_default_with_none(self):
+        default_value = blocks.RawHTMLBlock(default=None).get_default()
+        self.assertEqual(default_value, '')
+        self.assertTrue(isinstance(default_value, SafeText))
+
+    def test_get_default_with_empty_string(self):
+        default_value = blocks.RawHTMLBlock(default='').get_default()
+        self.assertEqual(default_value, '')
+        self.assertTrue(isinstance(default_value, SafeText))
+
+    def test_get_default_with_nonempty_string(self):
+        default_value = blocks.RawHTMLBlock(default='<blink>BOOM</blink>').get_default()
+        self.assertEqual(default_value, '<blink>BOOM</blink>')
+        self.assertTrue(isinstance(default_value, SafeText))
+
+    def test_serialize(self):
+        block = blocks.RawHTMLBlock()
+        result = block.get_prep_value(mark_safe('<blink>BOOM</blink>'))
+        self.assertEqual(result, '<blink>BOOM</blink>')
+
+    def test_deserialize(self):
+        block = blocks.RawHTMLBlock()
+        result = block.to_python('<blink>BOOM</blink>')
+        self.assertEqual(result, '<blink>BOOM</blink>')
+        self.assertTrue(isinstance(result, SafeText))
+
+    def test_render(self):
+        block = blocks.RawHTMLBlock()
+        result = block.render(mark_safe('<blink>BOOM</blink>'))
+        self.assertEqual(result, '<blink>BOOM</blink>')
+        self.assertTrue(isinstance(result, SafeText))
+
+    def test_render_form(self):
+        block = blocks.RawHTMLBlock()
+        result = block.render_form(mark_safe('<blink>BOOM</blink>'), prefix='rawhtml')
+        self.assertIn('<textarea ', result)
+        self.assertIn('name="rawhtml"', result)
+        self.assertIn('&lt;blink&gt;BOOM&lt;/blink&gt;', result)
+
+    def test_form_response(self):
+        block = blocks.RawHTMLBlock()
+        result = block.value_from_datadict({'rawhtml': '<blink>BOOM</blink>'}, {}, prefix='rawhtml')
+        self.assertEqual(result, '<blink>BOOM</blink>')
+        self.assertTrue(isinstance(result, SafeText))
+
+    def test_clean_required_field(self):
+        block = blocks.RawHTMLBlock()
+        result = block.clean(mark_safe('<blink>BOOM</blink>'))
+        self.assertEqual(result, '<blink>BOOM</blink>')
+        self.assertTrue(isinstance(result, SafeText))
+
+        with self.assertRaises(ValidationError):
+            block.clean(mark_safe(''))
+
+    def test_clean_nonrequired_field(self):
+        block = blocks.RawHTMLBlock(required=False)
+        result = block.clean(mark_safe('<blink>BOOM</blink>'))
+        self.assertEqual(result, '<blink>BOOM</blink>')
+        self.assertTrue(isinstance(result, SafeText))
+
+        result = block.clean(mark_safe(''))
+        self.assertEqual(result, '')
+        self.assertTrue(isinstance(result, SafeText))
+
+
 class TestMeta(unittest.TestCase):
     def test_set_template_with_meta(self):
         class HeadingBlock(blocks.CharBlock):