diff --color -ruN a/xembed-sni-proxy/sniproxy.cpp b/xembed-sni-proxy/sniproxy.cpp
--- a/xembed-sni-proxy/sniproxy.cpp	2026-10-04 00:18:30.351463483 +0200
+++ b/xembed-sni-proxy/sniproxy.cpp	2026-10-04 00:18:30.371083720 +0200
@@ -215,6 +215,33 @@
     QDBusConnection::disconnectFromBus(m_dbus.name());
 }
 
+// Crop the fully transparent margin around an icon, keeping the icon centred.
+// Wine, for one, draws a 16px icon in a 20px window; a tray that scales the whole
+// pixmap to its icon size then shows it smaller than every other icon.
+static QImage trimTransparentMargin(const QImage &image)
+{
+    if (!image.hasAlphaChannel()) {
+        return image;
+    }
+
+    const int w = image.width();
+    const int h = image.height();
+    int margin = std::min(w, h);
+    for (int y = 0; y < h; ++y) {
+        for (int x = 0; x < w; ++x) {
+            if (qAlpha(image.pixel(x, y)) != 0) {
+                margin = std::min({margin, x, y, w - 1 - x, h - 1 - y});
+            }
+        }
+    }
+
+    // nothing to trim, or nothing but margin
+    if (margin <= 0 || margin * 2 >= std::min(w, h)) {
+        return image;
+    }
+    return image.copy(margin, margin, w - 2 * margin, h - 2 * margin);
+}
+
 void SNIProxy::update()
 {
     QImage image = getImageNonComposite();
@@ -222,6 +249,7 @@
         qCDebug(SNIPROXY) << "No xembed icon for" << m_windowId << Title();
         return;
     }
+    image = trimTransparentMargin(image);
 
     int w = image.width();
     int h = image.height();