diff --git a/.github/workflows/ci-linux.yml b/.github/workflows/ci-linux.yml
index bf6b2397..2afc669d 100644
--- a/.github/workflows/ci-linux.yml
+++ b/.github/workflows/ci-linux.yml
@@ -45,12 +45,12 @@ jobs:
         uses: actions/cache@v1  # not v2!
         with:
           path: ../Qt
-          key: ${{ runner.os }}-QtCache-5.12-1
+          key: ${{ runner.os }}-QtCache-5.15
 
       - name: Install Qt
         uses: jurplel/install-qt-action@v2
         with:
-          version: 5.12.12
+          version: 5.15.2
           target: desktop
           modules: qtwebengine
           tools: tools_openssl_x64,1.1.1-4,qt.tools.openssl.gcc_64
diff --git a/src/widgets/viewwindow.cpp b/src/widgets/viewwindow.cpp
index ddfd6e9f..e2c8506a 100644
--- a/src/widgets/viewwindow.cpp
+++ b/src/widgets/viewwindow.cpp
@@ -41,11 +41,17 @@
 
 using namespace vnotex;
 
+QIcon ViewWindow::s_savedIcon;
+
+QIcon ViewWindow::s_modifiedIcon;
+
 ViewWindow::ViewWindow(QWidget *p_parent)
     : QFrame(p_parent)
 {
     setupUI();
 
+    initIcons();
+
     setupShortcuts();
 
     // Need to use this global-wise way, especially for the WebView.
@@ -96,6 +102,20 @@ void ViewWindow::setupUI()
     m_mainLayout->addLayout(m_bottomLayout, 0);
 }
 
+void ViewWindow::initIcons()
+{
+    if (!s_savedIcon.isNull()) {
+        return;
+    }
+
+    const auto &themeMgr = VNoteX::getInst().getThemeMgr();
+    const QString savedIconName("buffer.svg");
+    const QString unsavedIconFg("base#icon#warning#fg");
+    s_savedIcon = IconUtils::fetchIcon(themeMgr.getIconFile(savedIconName));
+    s_modifiedIcon = IconUtils::fetchIcon(themeMgr.getIconFile(savedIconName),
+                                          themeMgr.paletteColor(unsavedIconFg));
+}
+
 Buffer *ViewWindow::getBuffer() const
 {
     return m_buffer;
@@ -174,8 +194,11 @@ void ViewWindow::detachFromBuffer(bool p_quiet)
 
 QIcon ViewWindow::getIcon() const
 {
-    // Unnecessary to provide an icon for the tab.
-    return QIcon();
+    if (m_buffer) {
+        return m_buffer->isModified() ? s_modifiedIcon : s_savedIcon;
+    } else {
+        return s_savedIcon;
+    }
 }
 
 QString ViewWindow::getName() const
diff --git a/src/widgets/viewwindow.h b/src/widgets/viewwindow.h
index a2ac0ea8..da8e1f3d 100644
--- a/src/widgets/viewwindow.h
+++ b/src/widgets/viewwindow.h
@@ -283,6 +283,8 @@ namespace vnotex
 
         void setupUI();
 
+        void initIcons();
+
         void setupShortcuts();
 
         void discardChangesAndRead();
@@ -376,6 +378,9 @@ namespace vnotex
         QActionGroup *m_imageHostActionGroup = nullptr;
 
         bool m_statusWidgetInBottomLayout = false;
+
+        static QIcon s_savedIcon;
+        static QIcon s_modifiedIcon;
     };
 } // ns vnotex