diff --git a/autotests/foldingtest.cpp b/autotests/foldingtest.cpp
--- a/autotests/foldingtest.cpp
+++ b/autotests/foldingtest.cpp
@@ -178,16 +178,10 @@
         highlighter.setDefinition(def);
         highlighter.highlightFile(inFile, outFile);
 
-        const auto diffExecutable = QStandardPaths::findExecutable(QStringLiteral("diff"));
-        if (!diffExecutable.isEmpty()) {
-            QProcess proc;
-            proc.setProcessChannelMode(QProcess::ForwardedChannels);
-            proc.start(diffExecutable, {QStringLiteral("-u"), refFile, outFile});
-            QVERIFY(proc.waitForFinished());
-            QCOMPARE(proc.exitCode(), 0);
-        } else {
-            qDebug() << "Skipping part of the test since the 'diff' executable is not in PATH";
-        }
+        /**
+         * compare results
+         */
+        compareFiles(refFile, outFile);
     }
 
 };
diff --git a/autotests/htmlhighlighter_test.cpp b/autotests/htmlhighlighter_test.cpp
--- a/autotests/htmlhighlighter_test.cpp
+++ b/autotests/htmlhighlighter_test.cpp
@@ -107,16 +107,10 @@
         highlighter.setOutputFile(outFile);
         highlighter.highlightFile(inFile);
 
-        const auto diffExecutable = QStandardPaths::findExecutable(QStringLiteral("diff"));
-        if (!diffExecutable.isEmpty()) {
-            QProcess proc;
-            proc.setProcessChannelMode(QProcess::ForwardedChannels);
-            proc.start(diffExecutable, {QStringLiteral("-u"), refFile, outFile});
-            QVERIFY(proc.waitForFinished());
-            QCOMPARE(proc.exitCode(), 0);
-        } else {
-            qDebug() << "Skipping part of the test since the 'diff' executable is not in PATH";
-        }
+        /**
+         * compare results
+         */
+        compareFiles(refFile, outFile);
     }
 
 };
diff --git a/autotests/test-config.h.in b/autotests/test-config.h.in
--- a/autotests/test-config.h.in
+++ b/autotests/test-config.h.in
@@ -21,7 +21,11 @@
     SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */
 
+#include <QFile>
+#include <QProcess>
+#include <QStandardPaths>
 #include <QString>
+#include <qtest.h>
 
 #include <repository.h>
 
@@ -34,12 +38,51 @@
  *
  * @param repository repository to init search paths
  */
-static void initRepositorySearchPaths(KSyntaxHighlighting::Repository &repository)
+void initRepositorySearchPaths(KSyntaxHighlighting::Repository &repository)
 {
 #ifdef HAS_SYNTAX_RESOURCE
     Q_UNUSED(repository)
 #else
     repository.addCustomSearchPath(QStringLiteral("@CMAKE_SOURCE_DIR@/data"));
     repository.addCustomSearchPath(QStringLiteral("@CMAKE_BINARY_DIR@/data"));
 #endif
 }
+
+/**
+ * helper to compare files
+ * @param refFile reference file
+ * @param outFile output file
+ */
+void compareFiles(const QString &refFile, const QString &outFile)
+{
+    /**
+     * quick compare, all fine, if no diffs!
+     */
+    QFile ref(refFile);
+    QFile out(outFile);
+    QVERIFY(ref.open(QIODevice::ReadOnly));
+    QVERIFY(out.open(QIODevice::ReadOnly));
+    const bool equalResults = ref.readAll() == out.readAll();
+    if (equalResults) {
+        return;
+    }
+
+    /**
+     * elaborate diff output, if possible
+     */
+    const auto diffExecutable = QStandardPaths::findExecutable(QStringLiteral("diff"));
+    if (!diffExecutable.isEmpty()) {
+        QProcess proc;
+        proc.setProcessChannelMode(QProcess::ForwardedChannels);
+        proc.start(diffExecutable, {QStringLiteral("-u"), refFile, outFile});
+        QVERIFY(proc.waitForFinished());
+        QCOMPARE(proc.exitCode(), 0);
+    } else {
+        qDebug() << "Skipping differences output as the 'diff' executable is not in the PATH";
+    }
+
+    /**
+     * if we arrive here, all lost!
+     */
+    QVERIFY(equalResults);
+}
diff --git a/autotests/testhighlighter.cpp b/autotests/testhighlighter.cpp
--- a/autotests/testhighlighter.cpp
+++ b/autotests/testhighlighter.cpp
@@ -33,8 +33,6 @@
 #include <QDirIterator>
 #include <QFile>
 #include <QObject>
-#include <QProcess>
-#include <QStandardPaths>
 #include <QTextStream>
 #include <qtest.h>
 
@@ -176,16 +174,10 @@
         highlighter.setDefinition(def);
         highlighter.highlightFile(inFile, outFile);
 
-        const auto diffExecutable = QStandardPaths::findExecutable(QStringLiteral("diff"));
-        if (!diffExecutable.isEmpty()) {
-            QProcess proc;
-            proc.setProcessChannelMode(QProcess::ForwardedChannels);
-            proc.start(diffExecutable, {QStringLiteral("-u"), refFile, outFile});
-            QVERIFY(proc.waitForFinished());
-            QCOMPARE(proc.exitCode(), 0);
-        } else {
-            qDebug() << "Skipping part of the test since the 'diff' executable is not in PATH";
-        }
+        /**
+         * compare results
+         */
+        compareFiles(refFile, outFile);
     }
 
 };
diff --git a/src/lib/abstracthighlighter.cpp b/src/lib/abstracthighlighter.cpp
--- a/src/lib/abstracthighlighter.cpp
+++ b/src/lib/abstracthighlighter.cpp
@@ -127,13 +127,12 @@
     auto defData = DefinitionData::get(d->m_definition);
     auto newState = state;
     auto stateData = StateData::get(newState);
-    if (stateData->m_defData && defData != stateData->m_defData) {
+    if (stateData->initialContext() && DefinitionData::get(stateData->initialContext()->definition()) != defData) {
         qCDebug(Log) << "Got invalid state, resetting.";
         stateData->clear();
     }
     if (stateData->isEmpty()) {
         stateData->push(defData->initialContext(), QStringList());
-        stateData->m_defData = defData;
     }
 
     // process empty lines
diff --git a/src/lib/state.cpp b/src/lib/state.cpp
--- a/src/lib/state.cpp
+++ b/src/lib/state.cpp
@@ -1,5 +1,6 @@
 /*
     Copyright (C) 2016 Volker Krause <vkrause@kde.org>
+    Copyright (C) 2018 Christoph Cullmann <cullmann@kde.org>
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the
@@ -38,46 +39,45 @@
 
 bool StateData::isEmpty() const
 {
-    Q_ASSERT(m_contextStack.size() == m_captureStack.size());
     return m_contextStack.isEmpty();
 }
 
 void StateData::clear()
 {
     m_contextStack.clear();
-    m_captureStack.clear();
 }
 
 int StateData::size() const
 {
-    Q_ASSERT(m_contextStack.size() == m_captureStack.size());
     return m_contextStack.size();
 }
 
 void StateData::push(Context *context, const QStringList &captures)
 {
     Q_ASSERT(context);
-    m_contextStack.push(context);
-    m_captureStack.push(captures);
-    Q_ASSERT(m_contextStack.size() == m_captureStack.size());
+    m_contextStack.push_back(qMakePair(context, captures));
 }
 
 void StateData::pop()
 {
-    m_contextStack.pop();
-    m_captureStack.pop();
+    m_contextStack.pop_back();
+}
+
+Context* StateData::initialContext() const
+{
+    return isEmpty() ? nullptr : m_contextStack.first().first;
 }
 
 Context* StateData::topContext() const
 {
     Q_ASSERT(!isEmpty());
-    return m_contextStack.top();
+    return m_contextStack.last().first;
 }
 
-QStringList StateData::topCaptures() const
+const QStringList &StateData::topCaptures() const
 {
     Q_ASSERT(!isEmpty());
-    return m_captureStack.top();
+    return m_contextStack.last().second;
 }
 
 State::State() :
@@ -102,7 +102,7 @@
 
 bool State::operator==(const State &other) const
 {
-    return d->m_contextStack == other.d->m_contextStack && d->m_captureStack == other.d->m_captureStack && d->m_defData == other.d->m_defData;
+    return d->m_contextStack == other.d->m_contextStack;
 }
 
 bool State::operator!=(const State &other) const
@@ -114,5 +114,5 @@
 {
     if (d->m_contextStack.isEmpty())
         return false;
-    return d->m_contextStack.top()->indentationBasedFoldingEnabled();
+    return d->m_contextStack.last().first->indentationBasedFoldingEnabled();
 }
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
@@ -1,5 +1,6 @@
 /*
     Copyright (C) 2016 Volker Krause <vkrause@kde.org>
+    Copyright (C) 2018 Christoph Cullmann <cullmann@kde.org>
 
     Permission is hereby granted, free of charge, to any person obtaining
     a copy of this software and associated documentation files (the
@@ -25,7 +26,7 @@
 #define KSYNTAXHIGHLIGHTING_STATE_P_H
 
 #include <QSharedData>
-#include <QStack>
+#include <QVector>
 
 QT_BEGIN_NAMESPACE
 class QStringList;
@@ -39,6 +40,8 @@
 
 class StateData : public QSharedData
 {
+    friend class State;
+
 public:
     StateData() = default;
     static StateData* get(State &state);
@@ -48,14 +51,15 @@
     int size() const;
     void push(Context *context, const QStringList &captures);
     void pop();
+    Context* initialContext() const;
     Context* topContext() const;
-    QStringList topCaptures() const;
+    const QStringList &topCaptures() const;
 
-    DefinitionData *m_defData = nullptr;
 private:
-    friend class State;
-    QStack<Context*> m_contextStack;
-    QStack<QStringList> m_captureStack;
+    /**
+     * the context stack combines the active context + valid captures
+     */
+    QVector<QPair<Context *, QStringList>> m_contextStack;
 };
 
 }