diff --git a/deb/usr/share/applications/imajviewer.desktop b/deb/usr/share/applications/imajviewer.desktop
index 9e94813..8a67120 100644
--- a/deb/usr/share/applications/imajviewer.desktop
+++ b/deb/usr/share/applications/imajviewer.desktop
@@ -8,4 +8,4 @@ Terminal=false
 Categories=Graphics;Viewer;RasterGraphics;
 MimeType=image/png;image/jpeg;image/webp;image/bmp;image/gif;image/jpg;image/vnd.wap.wbmp;
 StartupNotify=false
-StartupWMClass=com.example.imajviewer
+StartupWMClass=Com.example.imajviewer
diff --git a/deb/usr/share/icons/hicolor/index.theme b/deb/usr/share/icons/hicolor/index.theme
new file mode 100644
index 0000000..9740d0e
--- /dev/null
+++ b/deb/usr/share/icons/hicolor/index.theme
@@ -0,0 +1,9 @@
+[Icon Theme]
+Name=Hicolor
+Comment=Fallback icon theme
+Directories=64x64/apps
+
+[64x64/apps]
+Size=64
+Context=Applications
+Type=Fixed
diff --git a/dist/imajviewer_1.0.0_amd64.deb b/dist/imajviewer_1.0.0_amd64.deb
index 1360c02..c78b130 100644
Binary files a/dist/imajviewer_1.0.0_amd64.deb and b/dist/imajviewer_1.0.0_amd64.deb differ
diff --git a/dist/rebuild-deb.sh b/dist/rebuild-deb.sh
index 2e4fa11..c0f5b15 100644
--- a/dist/rebuild-deb.sh
+++ b/dist/rebuild-deb.sh
@@ -27,6 +27,10 @@ echo "• .desktop dosyası kaynaktan kopyalanıyor…"
 DESKTOP_FILE="$TMPDIR/pkg/usr/share/applications/${APP}.desktop"
 cp "${PROJECT_DIR}/deb/usr/share/applications/${APP}.desktop" "$DESKTOP_FILE"
 
+echo "• İkonlar ve hicolor tema indeksi kopyalanıyor…"
+mkdir -p "$TMPDIR/pkg/usr/share/icons/hicolor"
+cp -r "${PROJECT_DIR}/deb/usr/share/icons/hicolor/." "$TMPDIR/pkg/usr/share/icons/hicolor/"
+
 echo "• Yeni .deb paketi oluşturuluyor…"
 fakeroot dpkg-deb --build "$TMPDIR/pkg" "${DEB}.tmp" >/dev/null
 mv "${DEB}.tmp" "$DEB"
diff --git a/install.sh b/install.sh
index fe8a949..f541e03 100755
--- a/install.sh
+++ b/install.sh
@@ -63,6 +63,22 @@ else
   ok "İkon zaten mevcut"
 fi
 
+# ── Hicolor tema indeksi (GTK ikon temasını tanısın) ──
+if [ ! -f "${HOME}/.local/share/icons/hicolor/index.theme" ]; then
+  mkdir -p "${HOME}/.local/share/icons/hicolor/64x64/apps"
+  cat > "${HOME}/.local/share/icons/hicolor/index.theme" << 'EOF'
+[Icon Theme]
+Name=Hicolor
+Comment=Fallback icon theme
+Directories=64x64/apps
+
+[64x64/apps]
+Size=64
+Context=Applications
+Type=Fixed
+EOF
+fi
+
 # ── .desktop dosyası ──
 info ".desktop dosyası oluşturuluyor…"
 cat > "$DESKTOP_FILE" << EOF
@@ -76,7 +92,7 @@ Terminal=false
 Categories=Graphics;Viewer;RasterGraphics;
 MimeType=image/png;image/jpeg;image/webp;image/bmp;image/gif;image/jpg;image/vnd.wap.wbmp;
 StartupNotify=false
-StartupWMClass=com.example.imajviewer
+StartupWMClass=Com.example.imajviewer
 EOF
 ok "${DESKTOP_FILE}"
 
diff --git a/linux/CMakeLists.txt b/linux/CMakeLists.txt
index ed63d18..704f574 100644
--- a/linux/CMakeLists.txt
+++ b/linux/CMakeLists.txt
@@ -121,6 +121,12 @@ install(CODE "
 install(DIRECTORY "${PROJECT_BUILD_DIR}/${FLUTTER_ASSET_DIR_NAME}"
   DESTINATION "${INSTALL_BUNDLE_DATA_DIR}" COMPONENT Runtime)
 
+# Bundle the application icon so the runner can set the window icon at runtime.
+install(FILES "${PROJECT_SOURCE_DIR}/../imajviewericon.png"
+        DESTINATION "${INSTALL_BUNDLE_DATA_DIR}"
+        RENAME "imajviewer.png"
+        COMPONENT Runtime)
+
 # Install the AOT library on non-Debug builds only.
 if(NOT CMAKE_BUILD_TYPE MATCHES "Debug")
   install(FILES "${AOT_LIBRARY}" DESTINATION "${INSTALL_BUNDLE_LIB_DIR}"
diff --git a/linux/runner/my_application.cc b/linux/runner/my_application.cc
index d7bd4e2..ee9b52b 100644
--- a/linux/runner/my_application.cc
+++ b/linux/runner/my_application.cc
@@ -156,6 +156,20 @@ MyApplication* my_application_new() {
   // the application to be recognized beyond its binary name.
   g_set_prgname(APPLICATION_ID);
 
+  // App-level default icon. GTK writes _NET_WM_ICON from this when windows
+  // are realized, so taskbars show the application icon.
+  g_autofree gchar* exe_path = g_file_read_link("/proc/self/exe", nullptr);
+  if (exe_path != nullptr) {
+    g_autofree gchar* bundle_dir = g_path_get_dirname(exe_path);
+    g_autofree gchar* icon_path =
+        g_build_filename(bundle_dir, "data", "imajviewer.png", nullptr);
+    GdkPixbuf* pixbuf = gdk_pixbuf_new_from_file(icon_path, nullptr);
+    if (pixbuf != nullptr) {
+      gtk_window_set_default_icon(pixbuf);
+      g_object_unref(pixbuf);
+    }
+  }
+
   return MY_APPLICATION(g_object_new(my_application_get_type(),
                                      "application-id", APPLICATION_ID, "flags",
                                      G_APPLICATION_NON_UNIQUE, nullptr));
diff --git a/windows/runner/resources/app_icon.ico b/windows/runner/resources/app_icon.ico
index 48be4f4..5d4bb1a 100644
Binary files a/windows/runner/resources/app_icon.ico and b/windows/runner/resources/app_icon.ico differ