diff --git a/src/session_consolekit.cpp b/src/session_consolekit.cpp
index d6c213788a..6fe7fcd31e 100644
--- a/src/session_consolekit.cpp
+++ b/src/session_consolekit.cpp
@@ -175,6 +175,8 @@ int ConsoleKitSession::openRestricted(const QString &fileName)
 
     const QDBusMessage reply = QDBusConnection::systemBus().call(message);
     if (reply.type() == QDBusMessage::ErrorMessage) {
+        qCDebug(KWIN_CORE, "Failed to open %s device (%s)",
+                qPrintable(fileName), qPrintable(reply.errorMessage()));
         return -1;
     }
 
diff --git a/src/session_logind.cpp b/src/session_logind.cpp
index 91a1f484b0..fc94f56434 100644
--- a/src/session_logind.cpp
+++ b/src/session_logind.cpp
@@ -181,6 +181,8 @@ int LogindSession::openRestricted(const QString &fileName)
 
     const QDBusMessage reply = QDBusConnection::systemBus().call(message);
     if (reply.type() == QDBusMessage::ErrorMessage) {
+        qCDebug(KWIN_CORE, "Failed to open %s device (%s)",
+                qPrintable(fileName), qPrintable(reply.errorMessage()));
         return -1;
     }