diff --git a/src/kiconloader.cpp b/src/kiconloader.cpp
--- a/src/kiconloader.cpp
+++ b/src/kiconloader.cpp
@@ -41,6 +41,7 @@
 #include <QMovie>
 #include <QPainter>
 #include <QPixmap>
+#include <QMutex>
 #include <QPixmapCache>
 
 // kdecore
@@ -569,21 +570,51 @@
     emit q->iconChanged(group);
 }
 
+class SafePrivate : public KIconLoaderPrivate
+{
+    struct Proxy
+    {
+        QMutex &mutex;
+        KIconLoaderPrivate *d;
+        Proxy(QMutex &m, KIconLoaderPrivate *p) : mutex(m), d(p)
+        {
+            mutex.lock();
+        }
+        ~Proxy()
+        {
+            mutex.unlock();
+        }
+        KIconLoaderPrivate* operator->()
+        {
+            return d;
+        }
+    };
+    QMutex mutex;
+public:
+    using KIconLoaderPrivate::KIconLoaderPrivate;
+    Proxy lock()
+    {
+        return Proxy{ mutex, this };
+    }
+};
+
+#define S_D(d) static_cast<SafePrivate*>(d)->lock()
+
 KIconLoader::KIconLoader(const QString &_appname, const QStringList &extraSearchPaths, QObject *parent)
     : QObject(parent)
 {
     setObjectName(_appname);
-    d = new KIconLoaderPrivate(this);
+    d = new SafePrivate(this);
 
     connect(s_globalData, SIGNAL(iconChanged(int)), SLOT(_k_refreshIcons(int)));
-    d->init(_appname, extraSearchPaths);
+    S_D(d)->init(_appname, extraSearchPaths);
 }
 
 void KIconLoader::reconfigure(const QString &_appname, const QStringList &extraSearchPaths)
 {
-    d->mIconCache->clear();
-    d->clear();
-    d->init(_appname, extraSearchPaths);
+    S_D(d)->mIconCache->clear();
+    S_D(d)->clear();
+    S_D(d)->init(_appname, extraSearchPaths);
 }
 
 void KIconLoaderPrivate::init(const QString &_appname, const QStringList &extraSearchPaths)
@@ -672,15 +703,15 @@
 
 QStringList KIconLoader::searchPaths() const
 {
-    return d->searchPaths;
+    return S_D(d)->searchPaths;
 }
 
 void KIconLoader::addAppDir(const QString &appname, const QString &themeBaseDir)
 {
-    d->initIconThemes();
+    S_D(d)->initIconThemes();
 
-    d->searchPaths.append(appname + QStringLiteral("/pics"));
-    d->addAppThemes(appname, themeBaseDir);
+    S_D(d)->searchPaths.append(appname + QStringLiteral("/pics"));
+    S_D(d)->addAppThemes(appname, themeBaseDir);
 }
 
 void KIconLoaderPrivate::addAppThemes(const QString &appname, const QString &themeBaseDir)
@@ -808,7 +839,7 @@
 
 void KIconLoader::drawOverlays(const QStringList &overlays, QPixmap &pixmap, KIconLoader::Group group, int state) const
 {
-    d->drawOverlays(this, group, state, pixmap, overlays);
+    S_D(d)->drawOverlays(this, group, state, pixmap, overlays);
 }
 
 QString KIconLoaderPrivate::removeIconExtension(const QString &name) const
@@ -1171,7 +1202,7 @@
 QString KIconLoader::iconPath(const QString &_name, int group_or_size,
                               bool canReturnNull, qreal scale) const
 {
-    if (!d->initIconThemes()) {
+    if (!S_D(d)->initIconThemes()) {
         return QString();
     }
 
@@ -1180,19 +1211,19 @@
         return _name;
     }
 
-    QString name = d->removeIconExtension(_name);
+    QString name = S_D(d)->removeIconExtension(_name);
 
     QString path;
     if (group_or_size == KIconLoader::User) {
-        path = d->locate(name + QLatin1String(".png"));
+        path = S_D(d)->locate(name + QLatin1String(".png"));
         if (path.isEmpty()) {
-            path = d->locate(name + QLatin1String(".svgz"));
+            path = S_D(d)->locate(name + QLatin1String(".svgz"));
         }
         if (path.isEmpty()) {
-            path = d->locate(name + QLatin1String(".svg"));
+            path = S_D(d)->locate(name + QLatin1String(".svg"));
         }
         if (path.isEmpty()) {
-            path = d->locate(name + QLatin1String(".xpm"));
+            path = S_D(d)->locate(name + QLatin1String(".xpm"));
         }
         return path;
     }
@@ -1204,7 +1235,7 @@
 
     int size;
     if (group_or_size >= 0) {
-        size = d->mpGroups[group_or_size].size;
+        size = S_D(d)->mpGroups[group_or_size].size;
     } else {
         size = -group_or_size;
     }
@@ -1213,11 +1244,11 @@
         if (canReturnNull) {
             return QString();
         } else {
-            return d->unknownIconPath(size, scale);
+            return S_D(d)->unknownIconPath(size, scale);
         }
     }
 
-    path = d->findMatchingIconWithGenericFallbacks(name, size, scale);
+    path = S_D(d)->findMatchingIconWithGenericFallbacks(name, size, scale);
 
     if (path.isEmpty()) {
         // Try "User" group too.
@@ -1226,7 +1257,7 @@
             return path;
         }
 
-        return d->unknownIconPath(size, scale);
+        return S_D(d)->unknownIconPath(size, scale);
     }
     return path;
 }
@@ -1240,12 +1271,12 @@
         iconName[slashindex] = QLatin1Char('-');
     }
 
-    if (!d->extraDesktopIconsLoaded) {
+    if (!S_D(d)->extraDesktopIconsLoaded) {
         const QPixmap pixmap = loadIcon(iconName, group, size, state, overlays, path_store, true);
         if (!pixmap.isNull()) {
             return pixmap;
         }
-        d->addExtraDesktopThemes();
+        S_D(d)->addExtraDesktopThemes();
     }
     const QPixmap pixmap = loadIcon(iconName, group, size, state, overlays, path_store, true);
     if (pixmap.isNull()) {
@@ -1293,7 +1324,7 @@
 
     bool absolutePath = !pathIsRelative(name);
     if (!absolutePath) {
-        name = d->removeIconExtension(name);
+        name = S_D(d)->removeIconExtension(name);
     }
 
     // Don't bother looking for an icon with no name.
@@ -1303,16 +1334,16 @@
 
     // May modify group, size, or state. This function puts them into sane
     // states.
-    d->normalizeIconMetadata(group, size, state);
+    S_D(d)->normalizeIconMetadata(group, size, state);
 
     // See if the image is already cached.
-    QString key = d->makeCacheKey(name, group, overlays, size, scale, state);
+    QString key = S_D(d)->makeCacheKey(name, group, overlays, size, scale, state);
     QPixmap pix;
 
     bool iconWasUnknown = false;
     QString path;
 
-    if (d->findCachedPixmapWithPath(key, pix, path)) {
+    if (S_D(d)->findCachedPixmapWithPath(key, pix, path)) {
         pix.setDevicePixelRatio(scale);
 
         if (path_store) {
@@ -1324,14 +1355,14 @@
         } else {
             // path is empty for "unknown" icons, which should be searched for
             // anew regularly
-            if (!d->shouldCheckForUnknownIcons()) {
+            if (!S_D(d)->shouldCheckForUnknownIcons()) {
                 return canReturnNull ? QPixmap() : pix;
             }
         }
     }
 
     // Image is not cached... go find it and apply effects.
-    if (!d->initIconThemes()) {
+    if (!S_D(d)->initIconThemes()) {
         return QPixmap();
     }
 
@@ -1343,7 +1374,7 @@
         if (absolutePath && !favIconOverlay) {
             path = name;
         } else {
-            path = d->findMatchingIconWithGenericFallbacks(favIconOverlay ? QStringLiteral("text-html") : name, size, scale);
+            path = S_D(d)->findMatchingIconWithGenericFallbacks(favIconOverlay ? QStringLiteral("text-html") : name, size, scale);
         }
     }
 
@@ -1356,17 +1387,17 @@
     // Still can't find it? Use "unknown" if we can't return null.
     // We keep going in the function so we can ensure this result gets cached.
     if (path.isEmpty() && !canReturnNull) {
-        path = d->unknownIconPath(size, scale);
+        path = S_D(d)->unknownIconPath(size, scale);
         iconWasUnknown = true;
     }
 
     QImage img;
     if (!path.isEmpty()) {
-        img = d->createIconImage(path, size, scale, static_cast<KIconLoader::States>(state));
+        img = S_D(d)->createIconImage(path, size, scale, static_cast<KIconLoader::States>(state));
     }
 
     if (group >= 0) {
-        img = d->mpEffect.apply(img, group, state);
+        img = S_D(d)->mpEffect.apply(img, group, state);
     }
 
     if (favIconOverlay) {
@@ -1389,7 +1420,7 @@
     // TODO: If we make a loadIcon that returns the image we can convert
     // drawOverlays to use the image instead of pixmaps as well so we don't
     // have to transfer so much to the graphics card.
-    d->drawOverlays(this, group, state, pix, overlays);
+    S_D(d)->drawOverlays(this, group, state, pix, overlays);
 
     // Don't add the path to our unknown icon to the cache, only cache the
     // actual image.
@@ -1397,7 +1428,7 @@
         path.clear();
     }
 
-    d->insertCachedPixmapWithPath(key, pix, path);
+    S_D(d)->insertCachedPixmapWithPath(key, pix, path);
 
     if (path_store) {
         *path_store = path;
@@ -1432,11 +1463,11 @@
 
 QString KIconLoader::moviePath(const QString &name, KIconLoader::Group group, int size) const
 {
-    if (!d->mpGroups) {
+    if (!S_D(d)->mpGroups) {
         return QString();
     }
 
-    d->initIconThemes();
+    S_D(d)->initIconThemes();
 
     if ((group < -1 || group >= KIconLoader::LastGroup) && group != KIconLoader::User) {
         qCDebug(KICONTHEMES) << "Illegal icon group:" << group;
@@ -1449,15 +1480,15 @@
 
     QString file = name + QStringLiteral(".mng");
     if (group == KIconLoader::User) {
-        file = d->locate(file);
+        file = S_D(d)->locate(file);
     } else {
         if (size == 0) {
-            size = d->mpGroups[group].size;
+            size = S_D(d)->mpGroups[group].size;
         }
 
         QString path;
 
-        foreach (KIconThemeNode *themeNode, d->links) {
+        foreach (KIconThemeNode *themeNode, S_D(d)->links) {
             path = themeNode->theme->iconPath(file, size, KIconLoader::MatchExact);
             if (!path.isEmpty()) {
                 break;
@@ -1465,7 +1496,7 @@
         }
 
         if (path.isEmpty()) {
-            foreach (KIconThemeNode *themeNode, d->links) {
+            foreach (KIconThemeNode *themeNode, S_D(d)->links) {
                 path = themeNode->theme->iconPath(file, size, KIconLoader::MatchBest);
                 if (!path.isEmpty()) {
                     break;
@@ -1482,11 +1513,11 @@
 {
     QStringList lst;
 
-    if (!d->mpGroups) {
+    if (!S_D(d)->mpGroups) {
         return lst;
     }
 
-    d->initIconThemes();
+    S_D(d)->initIconThemes();
 
     if ((group < -1) || (group >= KIconLoader::LastGroup)) {
         qCDebug(KICONTHEMES) << "Illegal icon group: " << group;
@@ -1499,12 +1530,12 @@
 
     QString file = name + QStringLiteral("/0001");
     if (group == KIconLoader::User) {
-        file = d->locate(file + QStringLiteral(".png"));
+        file = S_D(d)->locate(file + QStringLiteral(".png"));
     } else {
         if (size == 0) {
-            size = d->mpGroups[group].size;
+            size = S_D(d)->mpGroups[group].size;
         }
-        file = d->findMatchingIcon(file, size, 1); // FIXME scale
+        file = S_D(d)->findMatchingIcon(file, size, 1); // FIXME scale
     }
     if (file.isEmpty()) {
         return lst;
@@ -1529,16 +1560,16 @@
 
 KIconTheme *KIconLoader::theme() const
 {
-    d->initIconThemes();
-    if (d->mpThemeRoot) {
-        return d->mpThemeRoot->theme;
+    S_D(d)->initIconThemes();
+    if (S_D(d)->mpThemeRoot) {
+        return S_D(d)->mpThemeRoot->theme;
     }
     return nullptr;
 }
 
 int KIconLoader::currentSize(KIconLoader::Group group) const
 {
-    if (!d->mpGroups) {
+    if (!S_D(d)->mpGroups) {
         return -1;
     }
 
@@ -1546,7 +1577,7 @@
         qCDebug(KICONTHEMES) << "Illegal icon group:" << group;
         return -1;
     }
-    return d->mpGroups[group].size;
+    return S_D(d)->mpGroups[group].size;
 }
 
 QStringList KIconLoader::queryIconsByDir(const QString &iconsDir) const
@@ -1564,7 +1595,7 @@
 QStringList KIconLoader::queryIconsByContext(int group_or_size,
         KIconLoader::Context context) const
 {
-    d->initIconThemes();
+    S_D(d)->initIconThemes();
 
     QStringList result;
     if (group_or_size >= KIconLoader::LastGroup) {
@@ -1573,12 +1604,12 @@
     }
     int size;
     if (group_or_size >= 0) {
-        size = d->mpGroups[group_or_size].size;
+        size = S_D(d)->mpGroups[group_or_size].size;
     } else {
         size = -group_or_size;
     }
 
-    foreach (KIconThemeNode *themeNode, d->links) {
+    foreach (KIconThemeNode *themeNode, S_D(d)->links) {
         themeNode->queryIconsByContext(&result, size, context);
     }
 
@@ -1593,7 +1624,7 @@
         } else {
             name = (*it).mid(n + 1);
         }
-        name = d->removeIconExtension(name);
+        name = S_D(d)->removeIconExtension(name);
         if (!entries.contains(name)) {
             entries += name;
             res2 += *it;
@@ -1605,7 +1636,7 @@
 
 QStringList KIconLoader::queryIcons(int group_or_size, KIconLoader::Context context) const
 {
-    d->initIconThemes();
+    S_D(d)->initIconThemes();
 
     QStringList result;
     if (group_or_size >= KIconLoader::LastGroup) {
@@ -1614,12 +1645,12 @@
     }
     int size;
     if (group_or_size >= 0) {
-        size = d->mpGroups[group_or_size].size;
+        size = S_D(d)->mpGroups[group_or_size].size;
     } else {
         size = -group_or_size;
     }
 
-    foreach (KIconThemeNode *themeNode, d->links) {
+    foreach (KIconThemeNode *themeNode, S_D(d)->links) {
         themeNode->queryIcons(&result, size, context);
     }
 
@@ -1634,7 +1665,7 @@
         } else {
             name = (*it).mid(n + 1);
         }
-        name = d->removeIconExtension(name);
+        name = S_D(d)->removeIconExtension(name);
         if (!entries.contains(name)) {
             entries += name;
             res2 += *it;
@@ -1646,9 +1677,9 @@
 // used by KIconDialog to find out which contexts to offer in a combobox
 bool KIconLoader::hasContext(KIconLoader::Context context) const
 {
-    d->initIconThemes();
+    S_D(d)->initIconThemes();
 
-    foreach (KIconThemeNode *themeNode, d->links)
+    foreach (KIconThemeNode *themeNode, S_D(d)->links)
         if (themeNode->theme->hasContext(context)) {
             return true;
         }
@@ -1657,12 +1688,12 @@
 
 KIconEffect *KIconLoader::iconEffect() const
 {
-    return &d->mpEffect;
+    return &S_D(d)->mpEffect;
 }
 
 bool KIconLoader::alphaBlending(KIconLoader::Group group) const
 {
-    if (!d->mpGroups) {
+    if (!S_D(d)->mpGroups) {
         return false;
     }
 
@@ -1794,9 +1825,9 @@
 
 bool KIconLoader::hasIcon(const QString &name) const
 {
-    auto it = d->mIconAvailability.constFind(name);
-    const auto end = d->mIconAvailability.constEnd();
-    if (it != end && !it.value() && !d->shouldCheckForUnknownIcons()) {
+    auto it = S_D(d)->mIconAvailability.constFind(name);
+    const auto end = S_D(d)->mIconAvailability.constEnd();
+    if (it != end && !it.value() && !S_D(d)->shouldCheckForUnknownIcons()) {
         return false; // known to be unavailable
     }
     bool found = it != end && it.value();
@@ -1804,26 +1835,26 @@
         if (!iconPath(name, KIconLoader::Desktop, KIconLoader::MatchBest).isEmpty()) {
             found = true;
         }
-        d->mIconAvailability.insert(name, found); // remember whether the icon is available or not
+        S_D(d)->mIconAvailability.insert(name, found); // remember whether the icon is available or not
     }
     return found;
 }
 
 void KIconLoader::setCustomPalette(const QPalette &palette)
 {
-    d->mCustomPalette = true;
-    d->mPalette = palette;
+    S_D(d)->mCustomPalette = true;
+    S_D(d)->mPalette = palette;
 }
 
 QPalette KIconLoader::customPalette() const
 {
-    return d->mPalette;
+    return S_D(d)->mPalette;
 }
 
 void KIconLoader::resetPalette()
 {
-    d->mCustomPalette = false;
-    d->mPalette = QPalette();
+    S_D(d)->mCustomPalette = false;
+    S_D(d)->mPalette = QPalette();
 }
 
 /*** the global icon loader ***/