diff --git a/powerman/action.cpp b/powerman/action.cpp
index de64432..432eb86 100644
--- a/powerman/action.cpp
+++ b/powerman/action.cpp
@@ -48,6 +48,12 @@ void Action::registerIdleTimeout(int msec)
     IdleManager::self()->registerActionTimeout(this, msec);
 }
 
+void Action::unregisterIdleTimeout()
+{
+    d->registeredIdleTimeouts.clear();
+    IdleManager::self()->unregisterActionTimeouts(this);
+}
+
 bool Action::isSupported()
 {
     return true;
diff --git a/powerman/action.h b/powerman/action.h
index 141acac..56dc3f4 100644
--- a/powerman/action.h
+++ b/powerman/action.h
@@ -63,6 +63,8 @@ protected:
      */
     void registerIdleTimeout(int msec);
 
+    void unregisterIdleTimeout();
+
 public Q_SLOTS:
     /**
      * This slot is triggered whenever an idle timeout registered with registerIdleTimeout is reached.
diff --git a/powerman/dimdisplayaction.cpp b/powerman/dimdisplayaction.cpp
index 5f52efb..c0a3a1e 100644
--- a/powerman/dimdisplayaction.cpp
+++ b/powerman/dimdisplayaction.cpp
@@ -82,6 +82,13 @@ void DimDisplayAction::onIdleTimeout(int msec)
 
 void DimDisplayAction::setTimeout(int timeout)
 {
+    unregisterIdleTimeout();
+
+    if (timeout < 0) {
+        m_dimOnIdleTime = timeout;
+        return;
+    }
+
     m_dimOnIdleTime = timeout;
     registerIdleTimeout(m_dimOnIdleTime * 3 / 4);
     registerIdleTimeout(m_dimOnIdleTime / 2);