diff --git a/Dockerfile b/Dockerfile
index 78b2926..b59acdb 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -34,15 +34,12 @@ RUN mkdir tessdata && cd tessdata \
     && find . -name '*.traineddata' -maxdepth 2 -exec cp {} /usr/share/tessdata \; \
     && cd .. && rm -r tessdata
 
-RUN mkdir h2orestart && cd h2orestart \
+RUN mkdir /libreoffice_ext && cd libreoffice_ext \
     && H2ORESTART_FILENAME=h2orestart.oxt \
     && H2ORESTART_VERSION="v0.5.7" \
     && wget https://github.com/ebandal/H2Orestart/releases/download/$H2ORESTART_VERSION/$H2ORESTART_FILENAME \
     && echo "$H2ORESTART_CHECKSUM  $H2ORESTART_FILENAME" | sha256sum -c \
-    && _DESTDIR="/usr/lib/libreoffice/share/extensions/h2orestart/" \
-    && install -dm755 $_DESTDIR \
-    && unzip $H2ORESTART_FILENAME -d $_DESTDIR \
-    && cd .. && rm -r h2orestart
+    && install -dm777 "/usr/lib/libreoffice/share/extensions/"
 
 ENV PYTHONPATH=/opt/dangerzone
 
diff --git a/dangerzone/conversion/doc_to_pixels.py b/dangerzone/conversion/doc_to_pixels.py
index ac6055a..10e73ee 100644
--- a/dangerzone/conversion/doc_to_pixels.py
+++ b/dangerzone/conversion/doc_to_pixels.py
@@ -80,19 +80,24 @@ class DocumentToPixels(DangerzoneConverter):
             # .hwp
             "application/vnd.hancom.hwp": {
                 "type": "libreoffice",
+                "libreoffice_ext": "h2orestart.oxt",
             },
             "application/haansofthwp": {
                 "type": "libreoffice",
+                "libreoffice_ext": "h2orestart.oxt",
             },
             "application/x-hwp": {
                 "type": "libreoffice",
+                "libreoffice_ext": "h2orestart.oxt",
             },
             # .hwpx
             "application/vnd.hancom.hwpx": {
                 "type": "libreoffice",
+                "libreoffice_ext": "h2orestart.oxt",
             },
             "application/haansofthwpx": {
                 "type": "libreoffice",
+                "libreoffice_ext": "h2orestart.oxt",
             },
             "application/hwp+zip": {
                 "type": "libreoffice",
@@ -144,6 +149,9 @@ class DocumentToPixels(DangerzoneConverter):
         if conversion["type"] is None:
             pdf_filename = "/tmp/input_file"
         elif conversion["type"] == "libreoffice":
+            libreoffice_ext = conversion.get("libreoffice_ext", None)
+            if libreoffice_ext:
+                await self.install_libreoffice_ext(libreoffice_ext)
             self.update_progress("Converting to PDF using LibreOffice")
             args = [
                 "libreoffice",
@@ -303,6 +311,21 @@ class DocumentToPixels(DangerzoneConverter):
         ):
             shutil.move(filename, "/tmp/dangerzone")
 
+    async def install_libreoffice_ext(self, libreoffice_ext: str) -> None:
+        self.update_progress(f"Installing LibreOffice extension '{libreoffice_ext}'")
+        unzip_args = [
+            "unzip",
+            "-d",
+            f"/usr/lib/libreoffice/share/extensions/{libreoffice_ext}/",
+            f"/libreoffice_ext/{libreoffice_ext}",
+        ]
+        await run_command(
+            unzip_args,
+            error_message="LibreOffice extension installation failed (unzipping)",
+            timeout_message="unzipping LibreOffice extension timed out 5 seconds",
+            timeout=5,
+        )
+
 
 async def main() -> int:
     converter = DocumentToPixels()