diff --git a/dangerzone/__init__.py b/dangerzone/__init__.py
index 690564c..6d3d2d0 100644
--- a/dangerzone/__init__.py
+++ b/dangerzone/__init__.py
@@ -6,6 +6,7 @@ import platform
 import click
 import time
 import uuid
+import subprocess
 
 from .global_common import GlobalCommon
 from .main_window import MainWindow
@@ -39,12 +40,10 @@ class Application(QtWidgets.QApplication):
 
 
 @click.command()
+@click.option("--custom-container") # Use this container instead of flmcode/dangerzone
 @click.argument("filename", required=False)
-def main(filename):
-    print(f"dangerzone {dangerzone_version}")
-
-    # Allow Ctrl-C to smoothly quit the program instead of throwing an exception
-    signal.signal(signal.SIGINT, signal.SIG_DFL)
+def main(custom_container, filename):
+    click.echo(f"dangerzone {dangerzone_version}")
 
     # Create the Qt app
     app = Application()
@@ -53,20 +52,35 @@ def main(filename):
     # GlobalCommon object
     global_common = GlobalCommon(app)
 
+    if custom_container:
+        # Do we have this container?
+        output = subprocess.check_output(
+            [global_common.container_runtime, "image", "ls", custom_container],
+            startupinfo=global_common.get_subprocess_startupinfo(),
+        )
+        if custom_container.encode() not in output:
+            click.echo(f"Container '{container}' not found")
+            return
+
+        global_common.custom_container = custom_container
+
+    # Allow Ctrl-C to smoothly quit the program instead of throwing an exception
+    signal.signal(signal.SIGINT, signal.SIG_DFL)
+
     # If we're using Linux and docker, see if we need to add the user to the docker group
     if (
         platform.system() == "Linux"
         and global_common.container_runtime == "/usr/bin/docker"
     ):
         if not global_common.ensure_user_is_in_docker_group():
-            print("Failed to add user to docker group")
+            click.echo("Failed to add user to docker group")
             return
 
     # See if we need to install Docker...
     if (platform.system() == "Darwin" or platform.system() == "Windows") and (
         not is_docker_installed(global_common) or not is_docker_ready(global_common)
     ):
-        print("Docker is either not installed or not running")
+        click.echo("Docker is either not installed or not running")
         docker_installer = DockerInstaller(global_common)
         docker_installer.start()
         return
@@ -97,10 +111,10 @@ def main(filename):
             try:
                 open(filename, "rb")
             except FileNotFoundError:
-                print("File not found")
+                click.echo("File not found")
                 return False
             except PermissionError:
-                print("Permission denied")
+                click.echo("Permission denied")
                 return False
             window.common.document_filename = filename
             window.doc_selection_widget.document_selected.emit()
diff --git a/dangerzone/global_common.py b/dangerzone/global_common.py
index 819e8b7..f1d38d2 100644
--- a/dangerzone/global_common.py
+++ b/dangerzone/global_common.py
@@ -73,6 +73,9 @@ class GlobalCommon(object):
             else:
                 self.container_runtime = "/usr/bin/docker"
 
+        # In case we have a custom container
+        self.custom_container = None
+
         # Preload list of PDF viewers on computer
         self.pdf_viewers = self._find_pdf_viewers()
 
@@ -243,6 +246,12 @@ class GlobalCommon(object):
         # Load settings
         self.settings = Settings(self)
 
+    def get_container_name(self):
+        if self.custom_container:
+            return self.custom_container
+        else:
+            return "flmcode/dangerzone"
+
     def get_resource_path(self, filename):
         if getattr(sys, "dangerzone_dev", False):
             # Look for resources directory relative to python file
diff --git a/dangerzone/settings_widget.py b/dangerzone/settings_widget.py
index 76caf36..3e79020 100644
--- a/dangerzone/settings_widget.py
+++ b/dangerzone/settings_widget.py
@@ -135,13 +135,18 @@ class SettingsWidget(QtWidgets.QWidget):
             self.update_checkbox.setCheckState(QtCore.Qt.Unchecked)
 
         # Is update containers required?
-        output = subprocess.check_output(
-            [self.global_common.container_runtime, "image", "ls", "flmcode/dangerzone"],
-            startupinfo=self.global_common.get_subprocess_startupinfo(),
-        )
-        if b"dangerzone" not in output:
-            self.update_checkbox.setCheckState(QtCore.Qt.Checked)
+        if self.global_common.custom_container:
+            self.update_checkbox.setCheckState(QtCore.Qt.Unchecked)
             self.update_checkbox.setEnabled(False)
+            self.update_checkbox.hide()
+        else:
+            output = subprocess.check_output(
+                [self.global_common.container_runtime, "image", "ls", self.global_common.get_container_name()],
+                startupinfo=self.global_common.get_subprocess_startupinfo(),
+            )
+            if b"dangerzone" not in output:
+                self.update_checkbox.setCheckState(QtCore.Qt.Checked)
+                self.update_checkbox.setEnabled(False)
 
     def update_ui(self):
         if platform.system() == "Windows":
diff --git a/dangerzone/tasks.py b/dangerzone/tasks.py
index 3bb36e1..a3379c2 100644
--- a/dangerzone/tasks.py
+++ b/dangerzone/tasks.py
@@ -85,7 +85,7 @@ class ConvertToPixels(TaskBase):
             f"{self.common.document_filename}:/tmp/input_file",
             "-v",
             f"{self.common.pixel_dir.name}:/dangerzone",
-            "flmcode/dangerzone",
+            self.global_common.get_container_name(),
             "document-to-pixels",
         ]
         returncode, output = self.exec_container(args)
@@ -194,7 +194,7 @@ class ConvertToPDF(TaskBase):
                 f"{self.common.safe_dir.name}:/safezone",
             ]
             + envs
-            + ["flmcode/dangerzone", "pixels-to-pdf",]
+            + [self.global_common.get_container_name(), "pixels-to-pdf",]
         )
         returncode, output = self.exec_container(args)