diff --git a/main/ui/src/main/java/org/cryptomator/ui/controllers/UpgradeController.java b/main/ui/src/main/java/org/cryptomator/ui/controllers/UpgradeController.java
index 729f3fdf9..a34e2aeb6 100644
--- a/main/ui/src/main/java/org/cryptomator/ui/controllers/UpgradeController.java
+++ b/main/ui/src/main/java/org/cryptomator/ui/controllers/UpgradeController.java
@@ -15,11 +15,13 @@ import org.cryptomator.ui.settings.Localization;
 import org.cryptomator.ui.util.AsyncTaskService;
 import org.fxmisc.easybind.EasyBind;
 
+import javafx.beans.binding.BooleanExpression;
 import javafx.beans.property.ObjectProperty;
 import javafx.beans.property.SimpleObjectProperty;
 import javafx.event.ActionEvent;
 import javafx.fxml.FXML;
 import javafx.scene.control.Button;
+import javafx.scene.control.CheckBox;
 import javafx.scene.control.Label;
 import javafx.scene.control.ProgressIndicator;
 
@@ -44,6 +46,9 @@ public class UpgradeController extends LocalizedFXMLViewController {
 	@FXML
 	private SecPasswordField passwordField;
 
+	@FXML
+	private CheckBox confirmationCheckbox;
+
 	@FXML
 	private Button upgradeButton;
 
@@ -59,7 +64,9 @@ public class UpgradeController extends LocalizedFXMLViewController {
 			return instruction.map(this::upgradeNotification).orElse("");
 		}).orElse(""));
 
-		upgradeButton.disableProperty().bind(passwordField.textProperty().isEmpty().or(passwordField.disabledProperty()));
+		BooleanExpression passwordProvided = passwordField.textProperty().isNotEmpty().and(passwordField.disabledProperty().not());
+		BooleanExpression syncFinished = confirmationCheckbox.selectedProperty();
+		upgradeButton.disableProperty().bind(passwordProvided.not().or(syncFinished.not()));
 
 		EasyBind.subscribe(vault, this::vaultDidChange);
 	}
diff --git a/main/ui/src/main/resources/css/linux_theme.css b/main/ui/src/main/resources/css/linux_theme.css
index 38f453feb..f3b2f3576 100644
--- a/main/ui/src/main/resources/css/linux_theme.css
+++ b/main/ui/src/main/resources/css/linux_theme.css
@@ -305,17 +305,17 @@
  ****************************************************************************/
 
 .check-box {
-	-fx-label-padding: 0 0 0 3;
+	-fx-label-padding: 0 0 0 6px;
 	-fx-text-fill: COLOR_TEXT;
 }
 .check-box > .box {
-	-fx-padding: 3;
+	-fx-padding: 3px;
 	-fx-background-color: COLOR_BORDER_DARK, #FFF;
 	-fx-background-insets: 0, 1;
 }
 .check-box > .box > .mark {
 	-fx-background-color: transparent;
-	-fx-padding: 4;
+	-fx-padding: 4px;
 	-fx-shape: "M-1,4, L-1,5.5 L3.5,8.5 L9,0 L9,-1 L7,-1 L3,6 L1,4 Z";
 }
 .check-box:selected > .box {
diff --git a/main/ui/src/main/resources/css/mac_theme.css b/main/ui/src/main/resources/css/mac_theme.css
index bb5fa2053..ffd4b637e 100644
--- a/main/ui/src/main/resources/css/mac_theme.css
+++ b/main/ui/src/main/resources/css/mac_theme.css
@@ -386,7 +386,7 @@
  ******************************************************************************/
 
 .check-box {
-    -fx-label-padding: 0 0 0 3px;
+    -fx-label-padding: 0 0 0 6px;
     -fx-text-fill: COLOR_TEXT;
 }
 .check-box > .box {
diff --git a/main/ui/src/main/resources/css/win_theme.css b/main/ui/src/main/resources/css/win_theme.css
index 72fa8cb53..0c0c29c84 100644
--- a/main/ui/src/main/resources/css/win_theme.css
+++ b/main/ui/src/main/resources/css/win_theme.css
@@ -354,7 +354,7 @@
  ******************************************************************************/
 
 .check-box {
-    -fx-label-padding: 0 0 0 3px;
+    -fx-label-padding: 0 0 0 6px;
     -fx-text-fill: COLOR_TEXT;
 }
 .check-box > .box {
diff --git a/main/ui/src/main/resources/fxml/upgrade.fxml b/main/ui/src/main/resources/fxml/upgrade.fxml
index 5d54014a3..24fc99d0a 100644
--- a/main/ui/src/main/resources/fxml/upgrade.fxml
+++ b/main/ui/src/main/resources/fxml/upgrade.fxml
@@ -17,6 +17,8 @@
 <?import javafx.scene.layout.ColumnConstraints?>
 <?import javafx.scene.layout.Pane?>
 <?import javafx.scene.layout.HBox?>
+<?import javafx.scene.layout.VBox?>
+<?import javafx.scene.control.CheckBox?>
 
 <GridPane vgap="12.0" hgap="12.0" prefWidth="400.0" xmlns:fx="http://javafx.com/fxml" cacheShape="true" cache="true">
 	<padding>
@@ -34,15 +36,17 @@
 		<Pane prefHeight="12.0" GridPane.rowIndex="1" GridPane.columnIndex="0" GridPane.columnSpan="2" cacheShape="true" cache="true">
 		</Pane>
 
-		<Label text="%unlock.label.password" cacheShape="true" cache="true" GridPane.rowIndex="2" GridPane.columnIndex="0" />
-		<SecPasswordField fx:id="passwordField" cacheShape="true" cache="true" GridPane.rowIndex="2" GridPane.columnIndex="1" />
+		<Label text="%unlock.label.password" GridPane.rowIndex="2" GridPane.columnIndex="0" cacheShape="true" cache="true" />
+		<SecPasswordField fx:id="passwordField" GridPane.rowIndex="2" GridPane.columnIndex="1" cacheShape="true" cache="true" />
+		
+		<CheckBox fx:id="confirmationCheckbox" text="%upgrade.confirmation.label" wrapText="true" GridPane.rowIndex="3" GridPane.columnIndex="0" GridPane.columnSpan="2" cacheShape="true" cache="true" />
 
-		<HBox alignment="CENTER_RIGHT" GridPane.hgrow="ALWAYS" GridPane.rowIndex="3" GridPane.columnIndex="0" GridPane.columnSpan="2" cacheShape="true" cache="true">
+		<HBox alignment="CENTER_RIGHT" GridPane.hgrow="ALWAYS" GridPane.rowIndex="4" GridPane.columnIndex="0" GridPane.columnSpan="2" cacheShape="true" cache="true">
 			<Button fx:id="upgradeButton" text="%upgrade.button" prefWidth="150.0" onAction="#didClickUpgradeButton" cacheShape="true" cache="true" />
 		</HBox>
 
-		<ProgressIndicator progress="-1" fx:id="progressIndicator" visible="false" cacheShape="true" cache="true" cacheHint="SPEED" GridPane.rowIndex="4" GridPane.columnIndex="0" GridPane.columnSpan="2" />
+		<ProgressIndicator progress="-1" fx:id="progressIndicator" visible="false" GridPane.rowIndex="5" GridPane.columnIndex="0" GridPane.columnSpan="2" cacheShape="true" cache="true" cacheHint="SPEED" />
 
-		<Label fx:id="errorLabel" wrapText="true" GridPane.rowIndex="5" GridPane.columnIndex="0" GridPane.columnSpan="2" cacheShape="true" cache="true" />
+		<Label fx:id="errorLabel" wrapText="true" GridPane.rowIndex="6" GridPane.columnIndex="0" GridPane.columnSpan="2" cacheShape="true" cache="true" />
 	</children>
 </GridPane>
diff --git a/main/ui/src/main/resources/localization/en.txt b/main/ui/src/main/resources/localization/en.txt
index 3fe3d213c..ec6c8f6bf 100644
--- a/main/ui/src/main/resources/localization/en.txt
+++ b/main/ui/src/main/resources/localization/en.txt
@@ -38,6 +38,7 @@ initialize.label.doNotForget=IMPORTANT: If you forget your password, there is no
 notfound.label=Vault couldn't be found. Has it been moved?
 
 # upgrade.fxml
+upgrade.confirmation.label=Yes, I've made sure that synchronization has finished
 upgrade.button=Upgrade vault
 
 upgrade.version3dropBundleExtension.msg=This vault needs to be migrated to a newer format.\n"%1$s" will be renamed to "%2$s".\nPlease make sure synchronization has finished before proceeding.