diff --git a/dangerzone/gui/logic.py b/dangerzone/gui/logic.py
index d13c227..c4be210 100644
--- a/dangerzone/gui/logic.py
+++ b/dangerzone/gui/logic.py
@@ -107,16 +107,16 @@ class DangerzoneGui(DangerzoneCore):
 class Alert(QtWidgets.QDialog):
     def __init__(
         self,
-        gui_common: DangerzoneGui,
+        dangerzone: DangerzoneGui,
         message: str,
         ok_text: str = "Ok",
         extra_button_text: str = None,
     ) -> None:
         super(Alert, self).__init__()
-        self.gui_common = gui_common
+        self.dangerzone = dangerzone
 
         self.setWindowTitle("dangerzone")
-        self.setWindowIcon(self.gui_common.get_window_icon())
+        self.setWindowIcon(self.dangerzone.get_window_icon())
         self.setModal(True)
 
         flags = (
diff --git a/dangerzone/gui/main_window.py b/dangerzone/gui/main_window.py
index d86e753..5c55766 100644
--- a/dangerzone/gui/main_window.py
+++ b/dangerzone/gui/main_window.py
@@ -14,7 +14,7 @@ from .. import container
 from ..container import convert
 from ..document import SAFE_EXTENSION, Document
 from ..util import get_resource_path, get_subprocess_startupinfo
-from .logic import DangerzoneGui
+from .logic import Alert, DangerzoneGui
 
 log = logging.getLogger(__name__)
 
@@ -78,7 +78,21 @@ class MainWindow(QtWidgets.QMainWindow):
         self.content_widget.show()
 
     def closeEvent(self, e: QtGui.QCloseEvent) -> None:
-        e.accept()
+        alert_widget = Alert(
+            self.dangerzone,
+            message="Some documents are still being converted.\n Are you sure you want to quit?",
+            ok_text="Abort conversions",
+        )
+        converting_docs = self.dangerzone.get_converting_documents()
+        if not converting_docs:
+            e.accept()
+        else:
+            accept_exit = alert_widget.exec_()
+            if not accept_exit:
+                e.ignore()
+                return
+            else:
+                e.accept()
 
         if platform.system() != "Darwin":
             # in MacOS applications only quit when the user
diff --git a/dangerzone/logic.py b/dangerzone/logic.py
index 4fd6b06..cb17210 100644
--- a/dangerzone/logic.py
+++ b/dangerzone/logic.py
@@ -69,3 +69,6 @@ class DangerzoneCore(object):
 
     def get_failed_documents(self) -> List[Document]:
         return [doc for doc in self.documents if doc.is_failed()]
+
+    def get_converting_documents(self) -> List[Document]:
+        return [doc for doc in self.documents if doc.is_converting()]