diff --git a/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp b/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
index 118b4988a5..a5001f6e80 100644
--- a/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
+++ b/src/platformsupport/themes/genericunix/qgenericunixthemes.cpp
@@ -50,6 +50,7 @@
 #include <QtCore/QFile>
 #include <QtCore/QDebug>
 #include <QtCore/QHash>
+#include <QtCore/QMimeDatabase>
 #include <QtCore/QLoggingCategory>
 #include <QtCore/QSettings>
 #include <QtCore/QVariant>
@@ -231,6 +232,28 @@ QVariant QGenericUnixTheme::themeHint(ThemeHint hint) const
     return QPlatformTheme::themeHint(hint);
 }
 
+// Helper functions for implementing QPlatformTheme::fileIcon() for XDG icon themes.
+static QList<QSize> availableXdgFileIconSizes()
+{
+    return QIcon::fromTheme(QStringLiteral("inode-directory")).availableSizes();
+}
+
+static QIcon xdgFileIcon(const QFileInfo &fileInfo)
+{
+    QMimeDatabase mimeDatabase;
+    QMimeType mimeType = mimeDatabase.mimeTypeForFile(fileInfo);
+    if (!mimeType.isValid())
+        return QIcon();
+    const QString &iconName = mimeType.iconName();
+    if (!iconName.isEmpty()) {
+        const QIcon icon = QIcon::fromTheme(iconName);
+        if (!icon.isNull())
+            return icon;
+    }
+    const QString &genericIconName = mimeType.genericIconName();
+    return genericIconName.isEmpty() ? QIcon() : QIcon::fromTheme(genericIconName);
+}
+
 #ifndef QT_NO_SETTINGS
 class QKdeThemePrivate : public QPlatformThemePrivate
 {
@@ -506,6 +529,8 @@ QVariant QKdeTheme::themeHint(QPlatformTheme::ThemeHint hint) const
         return QVariant(d->iconFallbackThemeName);
     case QPlatformTheme::IconThemeSearchPaths:
         return QVariant(d->kdeIconThemeSearchPaths(d->kdeDirs));
+    case QPlatformTheme::IconPixmapSizes:
+        return QVariant::fromValue(availableXdgFileIconSizes());
     case QPlatformTheme::StyleNames:
         return QVariant(d->styleNames);
     case QPlatformTheme::KeyboardScheme:
@@ -520,6 +545,11 @@ QVariant QKdeTheme::themeHint(QPlatformTheme::ThemeHint hint) const
     return QPlatformTheme::themeHint(hint);
 }
 
+QIcon QKdeTheme::fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOptions) const
+{
+    return xdgFileIcon(fileInfo);
+}
+
 const QPalette *QKdeTheme::palette(Palette type) const
 {
     Q_D(const QKdeTheme);
@@ -657,6 +687,8 @@ QVariant QGnomeTheme::themeHint(QPlatformTheme::ThemeHint hint) const
         return QVariant(QStringLiteral("gnome"));
     case QPlatformTheme::IconThemeSearchPaths:
         return QVariant(QGenericUnixTheme::xdgIconThemePaths());
+    case QPlatformTheme::IconPixmapSizes:
+        return QVariant::fromValue(availableXdgFileIconSizes());
     case QPlatformTheme::StyleNames: {
         QStringList styleNames;
         styleNames << QStringLiteral("fusion") << QStringLiteral("windows");
@@ -674,6 +706,11 @@ QVariant QGnomeTheme::themeHint(QPlatformTheme::ThemeHint hint) const
     return QPlatformTheme::themeHint(hint);
 }
 
+QIcon QGnomeTheme::fileIcon(const QFileInfo &fileInfo, QPlatformTheme::IconOptions) const
+{
+    return xdgFileIcon(fileInfo);
+}
+
 const QFont *QGnomeTheme::font(Font type) const
 {
     Q_D(const QGnomeTheme);
diff --git a/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h b/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h
index 952658e130..da13390662 100644
--- a/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h
+++ b/src/platformsupport/themes/genericunix/qgenericunixthemes_p.h
@@ -107,6 +107,9 @@ public:
     static QPlatformTheme *createKdeTheme();
     QVariant themeHint(ThemeHint hint) const Q_DECL_OVERRIDE;
 
+    QIcon fileIcon(const QFileInfo &fileInfo,
+                   QPlatformTheme::IconOptions iconOptions = 0) const override;
+
     const QPalette *palette(Palette type = SystemPalette) const Q_DECL_OVERRIDE;
 
     const QFont *font(Font type) const Q_DECL_OVERRIDE;
@@ -129,6 +132,8 @@ class QGnomeTheme : public QPlatformTheme
 public:
     QGnomeTheme();
     QVariant themeHint(ThemeHint hint) const Q_DECL_OVERRIDE;
+    QIcon fileIcon(const QFileInfo &fileInfo,
+                   QPlatformTheme::IconOptions = 0) const override;
     const QFont *font(Font type) const Q_DECL_OVERRIDE;
     QString standardButtonText(int button) const Q_DECL_OVERRIDE;