diff --git a/tests/api/test_formdata.py b/tests/api/test_formdata.py
index b2e8af642..bef2e18ca 100644
--- a/tests/api/test_formdata.py
+++ b/tests/api/test_formdata.py
@@ -24,7 +24,12 @@ from wcs.qommon import ods
 from wcs.qommon.http_request import HTTPRequest
 from wcs.qommon.ident.password_accounts import PasswordAccount
 from wcs.qommon.upload_storage import PicklableUpload
-from wcs.workflows import EditableWorkflowStatusItem, Workflow, WorkflowBackofficeFieldsFormDef
+from wcs.workflows import (
+    AttachmentEvolutionPart,
+    EditableWorkflowStatusItem,
+    Workflow,
+    WorkflowBackofficeFieldsFormDef,
+)
 
 from ..utilities import clean_temporary_pub, create_temporary_pub, get_app, login
 from .utils import sign_uri
@@ -464,6 +469,56 @@ def test_formdata_with_workflow_data(pub, local_user):
     assert base64.decodebytes(force_bytes(resp.json['workflow']['data']['blah2']['content'])) == b'test'
 
 
+def test_formdata_with_evolution_part_attachment(pub, local_user):
+    pub.role_class.wipe()
+    role = pub.role_class(name='test')
+    role.id = '123'
+    role.store()
+
+    local_user.roles = [role.id]
+    local_user.store()
+
+    FormDef.wipe()
+    formdef = FormDef()
+    formdef.name = 'test'
+    formdef.fields = []
+    workflow = Workflow.get_default_workflow()
+    workflow.id = '2'
+    workflow.store()
+    formdef.workflow_id = workflow.id
+    formdef.workflow_roles = {'_receiver': role.id}
+    formdef.store()
+
+    formdef.data_class().wipe()
+    formdata = formdef.data_class()()
+    formdata.just_created()
+    formdata.status = 'wf-new'
+    formdata.evolution[-1].status = 'wf-new'
+    formdata.evolution[-1].parts = [
+        AttachmentEvolutionPart(
+            'hello.txt', fp=io.BytesIO(b'test'), content_type='text/plain', varname='testfile'
+        )
+    ]
+    formdata.store()
+
+    resp = get_app(pub).get(sign_uri('/api/forms/test/%s/' % formdata.id, user=local_user))
+    assert len(resp.json['evolution']) == 1
+    assert len(resp.json['evolution'][0]['parts']) == 1
+    part = resp.json['evolution'][0]['parts'][0]
+    assert part['filename'] == 'hello.txt'
+    assert part['content_type'] == 'text/plain'
+    assert 'content' in part
+    assert base64.decodebytes(force_bytes(part['content'])) == b'test'
+
+    resp = get_app(pub).get(sign_uri('/api/forms/test/%s/?anonymise' % formdata.id, user=local_user))
+    assert len(resp.json['evolution']) == 1
+    assert 'parts' not in resp.json['evolution']
+
+    # check this doesn't get into list of forms API
+    resp = get_app(pub).get(sign_uri('/api/forms/test/list?full=on', user=local_user))
+    assert 'hello.txt' not in resp.text
+
+
 def test_api_list_formdata(pub, local_user):
     pub.role_class.wipe()
     role = pub.role_class(name='test')
diff --git a/wcs/formdata.py b/wcs/formdata.py
index 8fea86fac..59fcf1b04 100644
--- a/wcs/formdata.py
+++ b/wcs/formdata.py
@@ -159,7 +159,7 @@ class Evolution:
         self._display_parts = l
         return self._display_parts
 
-    def get_json_export_dict(self, user, anonymise=False):
+    def get_json_export_dict(self, user, anonymise=False, include_files=True):
         data = {
             'time': datetime.datetime(*self.time[:6]) if self.time else None,
             'last_jump_datetime': self.last_jump_datetime,
@@ -180,7 +180,10 @@ class Evolution:
         parts = []
         for part in self.parts or []:
             if hasattr(part, 'get_json_export_dict'):
-                parts.append(part.get_json_export_dict(anonymise=anonymise))
+                d = part.get_json_export_dict(anonymise=anonymise, include_files=include_files)
+                if d:
+                    parts.append(d)
+
         if parts:
             data['parts'] = parts
         return data
@@ -1213,7 +1216,13 @@ class FormData(StorableObject):
         if self.evolution:
             evolution = data['evolution'] = []
             for evo in self.evolution:
-                evolution.append(evo.get_json_export_dict(None if anonymise else user, anonymise=anonymise))
+                evolution.append(
+                    evo.get_json_export_dict(
+                        user=None if anonymise else user,
+                        anonymise=anonymise,
+                        include_files=include_files,
+                    )
+                )
 
         if self.geolocations:
             data['geolocations'] = {}
diff --git a/wcs/wf/register_comment.py b/wcs/wf/register_comment.py
index 8549713ec..655b936dc 100644
--- a/wcs/wf/register_comment.py
+++ b/wcs/wf/register_comment.py
@@ -69,7 +69,7 @@ class JournalEvolutionPart:
                 + htmltext('</p>')
             )
 
-    def get_json_export_dict(self, anonymise=False):
+    def get_json_export_dict(self, anonymise=False, include_files=True):
         d = {
             'type': 'workflow-comment',
             'to': self.to,
diff --git a/wcs/wf/wscall.py b/wcs/wf/wscall.py
index 6fd8d792c..b22a5c722 100644
--- a/wcs/wf/wscall.py
+++ b/wcs/wf/wscall.py
@@ -94,7 +94,7 @@ class JournalWsCallErrorPart:
         r += htmltext('</div>')
         return r.getvalue()
 
-    def get_json_export_dict(self, anonymise=False):
+    def get_json_export_dict(self, anonymise=False, include_files=True):
         d = {
             'type': 'wscall-error',
         }
diff --git a/wcs/workflows.py b/wcs/workflows.py
index 4b6416c0d..677d406f4 100644
--- a/wcs/workflows.py
+++ b/wcs/workflows.py
@@ -271,6 +271,18 @@ class AttachmentEvolutionPart:
         else:
             return htmltext('<p class="wf-attachment">%s</p>' % self.orig_filename)
 
+    def get_json_export_dict(self, anonymise=False, include_files=True):
+        if not include_files or anonymise:
+            return None
+        d = {
+            'type': 'workflow-attachment',
+            'content_type': self.content_type,
+            'filename': self.base_filename,
+        }
+        with open(self.filename, 'rb') as fd:
+            d['content'] = base64.encodebytes(fd.read())
+        return d
+
     @classmethod
     def get_substitution_variables(cls, formdata):
         return {