diff --git a/src/kmainwindow.cpp b/src/kmainwindow.cpp
--- a/src/kmainwindow.cpp
+++ b/src/kmainwindow.cpp
@@ -239,6 +239,23 @@
 
     sMemberList()->append(q);
 
+    // Set the icon theme fallback to breeze
+    // Most of our apps use "lots" of icons that most of the times
+    // are only available with breeze, we still honour the user icon
+    // theme but if the icon is not found there, we go to breeze
+    // since it's almost sure it'll be there.
+    // Doing this as Q_COREAPP_STARTUP_FUNCTION is too soon as
+    // at that point QPlatformTheme is not instantiated yet and
+    // breaks the internal status of QIconLoader
+    // see https://bugreports.qt.io/browse/QTBUG-74252
+#if QT_VERSION >= QT_VERSION_CHECK(5, 12, 0)
+    static bool s_fallbackThemeInitialized = false;
+    if (!s_fallbackThemeInitialized) {
+        QIcon::setFallbackThemeName(QStringLiteral("breeze"));
+        s_fallbackThemeInitialized = true;
+    }
+#endif
+
     // If application is translated, load translator information for use in
     // KAboutApplicationDialog or other getters. The context and messages below
     // both must be exactly as listed, and are forced to be loaded from the