diff --git a/dangerzone/docker_installer.py b/dangerzone/docker_installer.py
index b1f043a..db07a23 100644
--- a/dangerzone/docker_installer.py
+++ b/dangerzone/docker_installer.py
@@ -11,6 +11,10 @@ from PyQt5 import QtCore, QtGui, QtWidgets
 from .container import container_runtime
 
 
+class AuthorizationFailed(Exception):
+    pass
+
+
 def is_docker_installed(global_common):
     if platform.system() == "Darwin":
         # Does the docker binary exist?
@@ -29,15 +33,18 @@ def is_docker_installed(global_common):
 
 def is_docker_ready(global_common):
     # Run `docker image ls` without an error
-    try:
-        print(global_common.get_dangerzone_container_args())
-        subprocess.run(
-            global_common.get_dangerzone_container_args() + ["image-ls"],
-            startupinfo=global_common.get_subprocess_startupinfo(),
-        )
-        return True
-    except subprocess.CalledProcessError:
-        return False
+    with global_common.exec_dangerzone_container(["image-ls"]) as p:
+        p.communicate()
+
+        # The user canceled, or permission denied
+        if p.returncode == 126 or p.returncode == 127:
+            raise AuthorizationFailed
+
+        # Return true if it succeeds
+        if p.returncode == 0:
+            return True
+        else:
+            return False
 
 
 def launch_docker_windows(global_common):
diff --git a/dangerzone/global_common.py b/dangerzone/global_common.py
index 95e6934..26dd061 100644
--- a/dangerzone/global_common.py
+++ b/dangerzone/global_common.py
@@ -6,6 +6,7 @@ import appdirs
 import platform
 import subprocess
 import shlex
+import pipes
 from PyQt5 import QtCore, QtGui, QtWidgets
 
 if platform.system() == "Darwin":
@@ -284,14 +285,25 @@ class GlobalCommon(object):
             else:
                 return "/usr/bin/dangerzone-container"
 
-    def get_dangerzone_container_args(self):
+    def exec_dangerzone_container(self, args):
+        # Prefix the args with the retainer runtime, and in the case linux when the user isn't in the docker group, pkexec
         if platform.system() == "Linux":
             if self.settings.get("linux_prefers_typing_password"):
-                return ["/usr/bin/pkexec", self.dz_container_path]
+                args = ["/usr/bin/pkexec", self.dz_container_path] + args
             else:
-                return [self.dz_container_path]
+                args = [self.dz_container_path] + args
         else:
-            return [self.dz_container_path]
+            args = [self.dz_container_path] + args
+
+        # Execute dangerzone-container
+        args_str = " ".join(pipes.quote(s) for s in args)
+        print(f"Executing: {args_str}")
+        return subprocess.Popen(
+            args,
+            startupinfo=self.get_subprocess_startupinfo(),
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+        )
 
     def get_window_icon(self):
         if platform.system() == "Windows":
diff --git a/dangerzone/gui.py b/dangerzone/gui.py
index 7aaf6dc..9d2d7db 100644
--- a/dangerzone/gui.py
+++ b/dangerzone/gui.py
@@ -15,6 +15,7 @@ from .docker_installer import (
     is_docker_ready,
     launch_docker_windows,
     DockerInstaller,
+    AuthorizationFailed,
 )
 from .container import container_runtime
 
@@ -51,14 +52,23 @@ def gui_main(custom_container, filename):
 
     if custom_container:
         # Do we have this container?
-        output = subprocess.check_output(
-            global_common.get_dangerzone_container_args()
-            + ["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
+        with global_common.exec_dangerzone_container(
+            ["image-ls", "--container-name", custom_container]
+        ) as p:
+            stdout_data, stderr_data = p.communicate()
+
+            # The user canceled, or permission denied
+            if p.returncode == 126 or p.returncode == 127:
+                click.echo("Authorization failed")
+                return
+            elif p.returncode != 0:
+                click.echo("Container error")
+                return
+
+            # Check the output
+            if custom_container.encode() not in stdout_data:
+                click.echo(f"Container '{container}' not found")
+                return
 
         global_common.custom_container = custom_container
 
@@ -69,8 +79,12 @@ def gui_main(custom_container, filename):
     if platform.system() == "Linux" and container_runtime == "/usr/bin/docker":
         if not global_common.ensure_docker_group_preference():
             return
-        if not global_common.ensure_docker_service_is_started():
-            click.echo("Failed to start docker service")
+        try:
+            if not global_common.ensure_docker_service_is_started():
+                click.echo("Failed to start docker service")
+                return
+        except AuthorizationFailed:
+            click.echo("Authorization failed")
             return
 
     # See if we need to install Docker...
diff --git a/dangerzone/main_window.py b/dangerzone/main_window.py
index dff53d0..38789d9 100644
--- a/dangerzone/main_window.py
+++ b/dangerzone/main_window.py
@@ -52,7 +52,11 @@ class MainWindow(QtWidgets.QMainWindow):
             self.settings_widget.document_selected
         )
         self.settings_widget.start_clicked.connect(self.start_clicked)
+        self.settings_widget.close_window.connect(self.close)
         self.settings_widget.hide()
+        QtCore.QTimer.singleShot(
+            1, self.settings_widget.check_update_container_default_state
+        )
 
         # Tasks
         self.tasks_widget = TasksWidget(self.global_common, self.common)
diff --git a/dangerzone/settings_widget.py b/dangerzone/settings_widget.py
index eecdbbc..ec7305c 100644
--- a/dangerzone/settings_widget.py
+++ b/dangerzone/settings_widget.py
@@ -6,6 +6,7 @@ from PyQt5 import QtCore, QtGui, QtWidgets
 
 class SettingsWidget(QtWidgets.QWidget):
     start_clicked = QtCore.pyqtSignal()
+    close_window = QtCore.pyqtSignal()
 
     def __init__(self, global_common, common):
         super(SettingsWidget, self).__init__()
@@ -134,24 +135,31 @@ class SettingsWidget(QtWidgets.QWidget):
         else:
             self.update_checkbox.setCheckState(QtCore.Qt.Unchecked)
 
+    def check_update_container_default_state(self):
         # Is update containers required?
         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.get_dangerzone_container_args()
-                + [
+            with self.global_common.exec_dangerzone_container(
+                [
                     "image-ls",
                     "--container-name",
                     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)
+                ]
+            ) as p:
+                stdout_data, stderror_data = p.communicate()
+
+                # The user canceled, or permission denied
+                if p.returncode == 126 or p.returncode == 127:
+                    self.close_window.emit()
+                    return
+
+                # Check the output
+                if b"dangerzone" not in stdout_data:
+                    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 fae33ae..1398203 100644
--- a/dangerzone/tasks.py
+++ b/dangerzone/tasks.py
@@ -16,29 +16,25 @@ class TaskBase(QtCore.QThread):
         super(TaskBase, self).__init__()
 
     def exec_container(self, args):
-        args = self.global_common.get_dangerzone_container_args() + args
         output = ""
         self.update_details.emit(output)
 
-        with subprocess.Popen(
-            args,
-            stdin=None,
-            stdout=subprocess.PIPE,
-            stderr=subprocess.PIPE,
-            bufsize=1,
-            universal_newlines=True,
-            startupinfo=self.global_common.get_subprocess_startupinfo(),
-        ) as p:
+        with self.global_common.exec_dangerzone_container(args) as p:
             for line in p.stdout:
-                output += line
-                print(line, end="")
+                output += line.decode()
+                print(line.decode(), end="")
                 self.update_details.emit(output)
 
             stderr = p.stderr.read()
-            output += stderr
-            print(stderr)
+            output += stderr.decode()
+            print(stderr.decode())
             self.update_details.emit(output)
 
+        if p.returncode == 126 or p.returncode == 127:
+            self.task_failed.emit(f"Authorization failed")
+        elif p.returncode == 0:
+            self.task_failed.emit(f"Return code: {p.returncode}")
+
         print("")
         return p.returncode, output
 
@@ -58,7 +54,6 @@ class PullImageTask(TaskBase):
         returncode, _ = self.exec_container(args)
 
         if returncode != 0:
-            self.task_failed.emit(f"Return code: {returncode}")
             return
 
         self.task_finished.emit()
@@ -88,7 +83,6 @@ class ConvertToPixels(TaskBase):
         returncode, output = self.exec_container(args)
 
         if returncode != 0:
-            self.task_failed.emit(f"Return code: {returncode}")
             return
 
         # Did we hit an error?
@@ -194,7 +188,6 @@ class ConvertToPDF(TaskBase):
         returncode, output = self.exec_container(args)
 
         if returncode != 0:
-            self.task_failed.emit(f"Return code: {returncode}")
             return
 
         self.task_finished.emit()