diff --git a/dangerzone/cli.py b/dangerzone/cli.py
index b305a11..45a7305 100644
--- a/dangerzone/cli.py
+++ b/dangerzone/cli.py
@@ -9,7 +9,7 @@ from colorama import Back, Fore, Style
 
 from . import args, container, errors
 from .container import convert
-from .document import Document
+from .document import SAFE_EXTENSION, Document
 from .global_common import GlobalCommon
 from .util import get_version
 
@@ -23,7 +23,7 @@ def print_header(s: str) -> None:
 @click.option(
     "--output-filename",
     callback=args.validate_output_filename,
-    help="Default is filename ending with -safe.pdf",
+    help=f"Default is filename ending with {SAFE_EXTENSION}",
 )
 @click.option("--ocr-lang", help="Language to OCR, defaults to none")
 @click.argument("filename", required=True, callback=args.validate_input_filename)
@@ -38,13 +38,11 @@ def cli_main(
 
     document = Document(filename)
 
-    # Validate safe PDF output filename
+    # Set PDF output filename
     if output_filename:
         document.output_filename = output_filename
     else:
-        document.output_filename = (
-            f"{os.path.splitext(document.input_filename)[0]}-safe.pdf"
-        )
+        document.set_default_output_filename()
 
     # Validate OCR language
     if ocr_lang:
diff --git a/dangerzone/document.py b/dangerzone/document.py
index 9d29fa7..6cfc28f 100644
--- a/dangerzone/document.py
+++ b/dangerzone/document.py
@@ -8,6 +8,8 @@ import appdirs
 
 from .errors import DocumentFilenameException
 
+SAFE_EXTENSION = "-safe.pdf"
+
 
 class Document:
     """Track the state of a single document.
@@ -75,3 +77,8 @@ class Document:
         filename = self.normalize_filename(filename)
         self.validate_output_filename(filename)
         self._output_filename = filename
+
+    def set_default_output_filename(self) -> None:
+        self.output_filename = (
+            f"{os.path.splitext(self.input_filename)[0]}{SAFE_EXTENSION}"
+        )
diff --git a/dangerzone/gui/main_window.py b/dangerzone/gui/main_window.py
index 436bac6..a425ee9 100644
--- a/dangerzone/gui/main_window.py
+++ b/dangerzone/gui/main_window.py
@@ -453,12 +453,9 @@ class SettingsWidget(QtWidgets.QWidget):
             f"Suspicious: {os.path.basename(self.document.input_filename)}"
         )
 
-        # Update the save location
-        output_filename = (
-            f"{os.path.splitext(self.document.input_filename)[0]}-safe.pdf"
-        )
-        self.document.output_filename = output_filename
-        self.save_lineedit.setText(os.path.basename(output_filename))
+        # Set the default save location
+        self.document.set_default_output_filename()
+        self.save_lineedit.setText(os.path.basename(self.document.output_filename))
 
     def save_browse_button_clicked(self) -> None:
         filename = QtWidgets.QFileDialog.getSaveFileName(
diff --git a/tests/__init__.py b/tests/__init__.py
index f11b309..dd32eac 100644
--- a/tests/__init__.py
+++ b/tests/__init__.py
@@ -6,13 +6,15 @@ import pytest
 
 sys.dangerzone_dev = True  # type: ignore[attr-defined]
 
+from dangerzone.document import SAFE_EXTENSION
+
 SAMPLE_DIRECTORY = "test_docs"
 BASIC_SAMPLE = "sample.pdf"
 test_docs_dir = Path(__file__).parent.joinpath(SAMPLE_DIRECTORY)
 test_docs = [
     p
     for p in test_docs_dir.rglob("*")
-    if p.is_file() and not p.name.endswith("-safe.pdf")
+    if p.is_file() and not p.name.endswith(SAFE_EXTENSION)
 ]
 
 # Pytest parameter decorators