diff --git a/rules.h b/rules.h
--- a/rules.h
+++ b/rules.h
@@ -293,7 +293,7 @@
 public:
     virtual ~RuleBook();
     WindowRules find(const AbstractClient*, bool);
-    void discardUsed(Client* c, bool withdraw);
+    void discardUsed(AbstractClient* c, bool withdraw);
     void setUpdatesDisabled(bool disable);
     bool areUpdatesDisabled() const;
     void load();
diff --git a/rules.cpp b/rules.cpp
--- a/rules.cpp
+++ b/rules.cpp
@@ -1108,7 +1108,7 @@
         QTimer::singleShot(60000, this, SLOT(cleanupTemporaryRules()));
 }
 
-void RuleBook::discardUsed(Client* c, bool withdrawn)
+void RuleBook::discardUsed(AbstractClient* c, bool withdrawn)
 {
     bool updated = false;
     for (QList< Rules* >::Iterator it = m_rules.begin();
diff --git a/workspace.cpp b/workspace.cpp
--- a/workspace.cpp
+++ b/workspace.cpp
@@ -851,8 +851,8 @@
     updateToolWindows(true);
 
     RuleBook::self()->load();
-    for (ClientList::Iterator it = clients.begin();
-            it != clients.end();
+    for (auto it = m_allClients.begin();
+            it != m_allClients.end();
             ++it) {
         (*it)->setupWindowRules(true);
         (*it)->applyWindowRules();