diff --git a/src/lib/abstracthighlighter.cpp b/src/lib/abstracthighlighter.cpp
--- a/src/lib/abstracthighlighter.cpp
+++ b/src/lib/abstracthighlighter.cpp
@@ -127,13 +127,14 @@
     auto defData = DefinitionData::get(d->m_definition);
     auto newState = state;
     auto stateData = StateData::get(newState);
-    if (stateData->m_defData && defData != stateData->m_defData) {
+    const DefinitionRef currentDefRef(d->m_definition);
+    if (!stateData->isEmpty() && (stateData->m_defRef != currentDefRef)) {
         qCDebug(Log) << "Got invalid state, resetting.";
         stateData->clear();
     }
     if (stateData->isEmpty()) {
         stateData->push(defData->initialContext(), QStringList());
-        stateData->m_defData = defData;
+        stateData->m_defRef = currentDefRef;
     }
 
     // process empty lines
diff --git a/src/lib/definition.cpp b/src/lib/definition.cpp
--- a/src/lib/definition.cpp
+++ b/src/lib/definition.cpp
@@ -783,3 +783,12 @@
         return Definition(d.lock());
     return Definition();
 }
+
+bool DefinitionRef::operator==(const DefinitionRef &other) const
+{
+    if (d.expired() != other.d.expired()) {
+        return false;
+    }
+
+    return d.expired() || d.lock().get() == other.d.lock().get();
+}
diff --git a/src/lib/definitionref_p.h b/src/lib/definitionref_p.h
--- a/src/lib/definitionref_p.h
+++ b/src/lib/definitionref_p.h
@@ -50,6 +50,19 @@
 
     Definition definition() const;
 
+    /**
+     * Checks two definition references for equality.
+     */
+    bool operator==(const DefinitionRef &other) const;
+
+    /**
+     * Checks two definition references for inequality.
+     */
+    bool operator!=(const DefinitionRef &other) const
+    {
+        return !(*this == other);
+    }
+
 private:
     friend class DefinitionData;
     std::weak_ptr<DefinitionData> d;
diff --git a/src/lib/state.cpp b/src/lib/state.cpp
--- a/src/lib/state.cpp
+++ b/src/lib/state.cpp
@@ -97,7 +97,8 @@
 
 bool State::operator==(const State &other) const
 {
-    return d->m_contextStack == other.d->m_contextStack && d->m_defData == other.d->m_defData;
+    // use pointer equal as shortcut for shared states
+    return (d == other.d) || (d->m_contextStack == other.d->m_contextStack && d->m_defRef == other.d->m_defRef);
 }
 
 bool State::operator!=(const State &other) const
diff --git a/src/lib/state_p.h b/src/lib/state_p.h
--- a/src/lib/state_p.h
+++ b/src/lib/state_p.h
@@ -28,19 +28,21 @@
 #include <QSharedData>
 #include <QVector>
 
+#include "definitionref_p.h"
+
 QT_BEGIN_NAMESPACE
 class QStringList;
 QT_END_NAMESPACE
 
 namespace KSyntaxHighlighting
 {
 
 class Context;
-class DefinitionData;
 
 class StateData : public QSharedData
 {
     friend class State;
+    friend class AbstractHighlighter;
 
 public:
     StateData() = default;
@@ -54,14 +56,11 @@
     Context* topContext() const;
     const QStringList &topCaptures() const;
 
+private:
     /**
-     * definition pointer to check for invalid states
-     * FIXME: this is a hack, one could get the same pointer
-     * later for other object
+     * weak reference to the used definition to filter out invalid states
      */
-    DefinitionData *m_defData = nullptr;
-
-private:
+    DefinitionRef m_defRef;
 
     /**
      * the context stack combines the active context + valid captures