diff --git a/docxtpl/subdoc.py b/docxtpl/subdoc.py
index e8da093..331e85d 100644
--- a/docxtpl/subdoc.py
+++ b/docxtpl/subdoc.py
@@ -5,6 +5,8 @@
 @author: Eric Lapouyade
 """
 
+from copy import deepcopy
+
 from docx import Document
 from docx.oxml import CT_SectPr
 from docx.opc.constants import RELATIONSHIP_TYPE as RT
@@ -13,7 +15,6 @@
 from docxcompose.composer import Composer
 from docxcompose.utils import NS
 from lxml import etree
-import re
 
 
 class SubdocComposer(Composer):
@@ -82,16 +83,19 @@ def __getattr__(self, name):
         return getattr(self.subdocx, name)
 
     def _get_xml(self):
-        if self.subdocx.element.body.sectPr is not None:
-            self.subdocx.element.body.remove(self.subdocx.element.body.sectPr)
-        xml = re.sub(
-            r"</?w:body[^>]*>",
-            "",
-            etree.tostring(
-                self.subdocx.element.body, encoding="unicode", pretty_print=False
-            ),
-        )
-        return xml
+        body = self.subdocx.element.body
+        if body.sectPr is not None:
+            body.remove(body.sectPr)
+        if len(body) == 0:
+            return ""
+
+        destination_body = self.docx.element.body
+        wrapper = etree.Element(destination_body.tag, nsmap=destination_body.nsmap)
+        for element in body:
+            wrapper.append(deepcopy(element))
+
+        xml = etree.tostring(wrapper, encoding="unicode", pretty_print=False)
+        return xml.partition(">")[2].rpartition("</")[0]
 
     def __unicode__(self):
         return self._get_xml()
diff --git a/tests/pandoc_subdoc.py b/tests/pandoc_subdoc.py
new file mode 100644
index 0000000..834dc6d
--- /dev/null
+++ b/tests/pandoc_subdoc.py
@@ -0,0 +1,119 @@
+import io
+import zipfile
+
+from docx import Document
+from docx.opc.constants import RELATIONSHIP_TYPE as RT
+from lxml import etree
+
+from docxtpl import DocxTemplate
+
+
+W_NS = "http://schemas.openxmlformats.org/wordprocessingml/2006/main"
+R_NS = "http://schemas.openxmlformats.org/officeDocument/2006/relationships"
+DEFAULT_NS = "urn:docxtpl:test-default"
+ATTRIBUTE_NS = "urn:docxtpl:test-attribute"
+CONFLICT_NS = "urn:docxtpl:test-conflict"
+
+
+def make_template():
+    document = Document()
+    document.add_paragraph("{{p subdoc }}")
+    stream = io.BytesIO()
+    document.save(stream)
+    stream.seek(0)
+    return DocxTemplate(stream)
+
+
+def render_to_stream(template, subdoc):
+    template.render({"subdoc": subdoc})
+    stream = io.BytesIO()
+    template.save(stream)
+    stream.seek(0)
+    return stream
+
+
+def document_xml(stream):
+    stream.seek(0)
+    with zipfile.ZipFile(stream) as archive:
+        return archive.read("word/document.xml")
+
+
+template = make_template()
+subdoc = template.new_subdoc("templates/pandoc_subdoc.docx")
+output_stream = render_to_stream(template, subdoc)
+
+document = Document(output_stream)
+assert len(document.inline_shapes) == 1
+image_relationships = [
+    relationship
+    for relationship in document.part.rels.values()
+    if relationship.reltype == RT.IMAGE
+]
+assert len(image_relationships) == 1
+
+root = etree.fromstring(document_xml(output_stream))
+assert root.find(".//{http://schemas.openxmlformats.org/drawingml/2006/main}graphic") is not None
+assert root.find(".//{http://schemas.openxmlformats.org/drawingml/2006/picture}pic") is not None
+image_reference = root.find(
+    ".//{http://schemas.openxmlformats.org/drawingml/2006/main}blip"
+)
+assert image_reference is not None
+image_relationship_id = image_reference.get("{%s}embed" % R_NS)
+assert image_relationship_id is not None
+assert document.part.rels[image_relationship_id].reltype == RT.IMAGE
+
+body = root.find("{%s}body" % W_NS)
+section_properties = body.findall("{%s}sectPr" % W_NS)
+assert len(section_properties) == 1
+assert body[-1] is section_properties[0]
+
+
+template = make_template()
+subdoc = template.new_subdoc()
+subdoc_body = subdoc.element.body
+subdoc_body.insert(
+    len(subdoc_body) - 1,
+    etree.Element("{%s}node" % DEFAULT_NS, nsmap={None: DEFAULT_NS}),
+)
+attributed_paragraph = etree.Element(
+    "{%s}p" % W_NS,
+    nsmap={"attribute": ATTRIBUTE_NS},
+)
+attributed_paragraph.set("{%s}flag" % ATTRIBUTE_NS, "yes")
+subdoc_body.insert(len(subdoc_body) - 1, attributed_paragraph)
+subdoc_body.insert(
+    len(subdoc_body) - 1,
+    etree.Element("{%s}node" % CONFLICT_NS, nsmap={"w": CONFLICT_NS}),
+)
+output_stream = render_to_stream(template, subdoc)
+root = etree.fromstring(document_xml(output_stream))
+
+assert root.find(".//{%s}node" % DEFAULT_NS) is not None
+assert any(
+    element.get("{%s}flag" % ATTRIBUTE_NS) == "yes"
+    for element in root.iter("{%s}p" % W_NS)
+)
+assert root.find(".//{%s}node" % CONFLICT_NS) is not None
+
+body = root.find("{%s}body" % W_NS)
+section_properties = body.findall("{%s}sectPr" % W_NS)
+assert len(section_properties) == 1
+assert body[-1] is section_properties[0]
+
+
+template = make_template()
+subdoc = template.new_subdoc()
+for _ in range(10000):
+    subdoc.add_paragraph("x")
+
+fragment = subdoc._get_xml()
+fragment_size = len(fragment.encode("utf-8"))
+assert fragment_size < 1000000, (
+    "subdocument fragment unexpectedly large: %d bytes" % fragment_size
+)
+
+fragment_body = etree.fromstring(
+    ('<w:body xmlns:w="%s">%s</w:body>' % (W_NS, fragment)).encode("utf-8")
+)
+assert len(fragment_body) == 10000
+assert all(element.tag == "{%s}p" % W_NS for element in fragment_body)
diff --git a/tests/runtests.py b/tests/runtests.py
index b0a3bf3..f6bdc2a 100644
--- a/tests/runtests.py
+++ b/tests/runtests.py
@@ -1,17 +1,48 @@
+from hashlib import sha256
+import json
+from pathlib import Path
 import subprocess
-import glob
-import os
+import sys
 
-tests = sorted(glob.glob("[A-Za-z]*.py"))
-excludes = ["runtests.py"]
 
-output_dir = os.path.join(os.path.dirname(__file__), "output")
-if not os.path.exists(output_dir):
-    os.mkdir(output_dir)
+def file_sha256(path):
+    digest = sha256()
+    with path.open("rb") as handle:
+        for chunk in iter(lambda: handle.read(1024 * 1024), b""):
+            digest.update(chunk)
+    return digest.hexdigest()
 
+
+tests_dir = Path(__file__).resolve().parent
+repo_root = tests_dir.parent
+launcher_path = Path(__file__).resolve()
+tests = sorted(
+    path
+    for path in tests_dir.glob("[A-Za-z]*.py")
+    if path.name != launcher_path.name
+)
+
+(tests_dir / "output").mkdir(exist_ok=True)
+records = []
 for test in tests:
-    if test not in excludes:
-        print("%s ..." % test)
-        subprocess.call(["python", "./%s" % test])
+    relative_path = test.relative_to(repo_root).as_posix()
+    test_sha256 = file_sha256(test)
+    print("RUN %s %s" % (relative_path, test_sha256), flush=True)
+    subprocess.run(
+        [sys.executable, str(test)],
+        cwd=str(tests_dir),
+        check=True,
+    )
+    print("PASS %s %s" % (relative_path, test_sha256), flush=True)
+    records.append({"path": relative_path, "sha256": test_sha256})
 
-print("Done.")
+completion = {
+    "status": "passed",
+    "count": len(records),
+    "launcher": {
+        "path": launcher_path.relative_to(repo_root).as_posix(),
+        "sha256": file_sha256(launcher_path),
+    },
+    "tests": records,
+}
+print(json.dumps(completion, sort_keys=True, separators=(",", ":")), flush=True)
diff --git a/tests/templates/pandoc_subdoc.docx b/tests/templates/pandoc_subdoc.docx
new file mode 100644
index 0000000..0816b38
Binary files /dev/null and b/tests/templates/pandoc_subdoc.docx differ