diff --git a/src/imagetoolbar.js b/src/imagetoolbar.js
index 964f1122..db15a971 100644
--- a/src/imagetoolbar.js
+++ b/src/imagetoolbar.js
@@ -59,11 +59,18 @@ export default class ImageToolbar extends Plugin {
 		const promises = [];
 		const toolbar = new ToolbarView();
 
+		// Add CSS class to the toolbar.
+		Template.extend( toolbar.template, {
+			attributes: {
+				class: 'ck-editor-toolbar'
+			}
+		} );
+
 		// Add CSS class to the panel.
 		Template.extend( panel.template, {
 			attributes: {
 				class: [
-					'ck-toolbar__container'
+					'ck-toolbar-container'
 				]
 			}
 		} );
diff --git a/tests/imagetoolbar.js b/tests/imagetoolbar.js
index ac3bcad6..529b519d 100644
--- a/tests/imagetoolbar.js
+++ b/tests/imagetoolbar.js
@@ -56,6 +56,11 @@ describe( 'ImageToolbar', () => {
 			} );
 	} );
 
+	it( 'should set css classes', () => {
+		expect( panel.element.classList.contains( 'ck-toolbar-container' ) ).to.be.true;
+		expect( panel.content.get( 0 ).element.classList.contains( 'ck-editor-toolbar' ) ).to.be.true;
+	} );
+
 	it( 'should add ImageBalloonPanel to view body', () => {
 		expect( panel ).to.be.instanceOf( ImageBalloonPanel );
 	} );