diff --git a/kate/ollie_ghost.cpp b/kate/ollie_ghost.cpp
index f74a898..f342bb5 100644
--- a/kate/ollie_ghost.cpp
+++ b/kate/ollie_ghost.cpp
@@ -1,6 +1,13 @@
 #include "ollie_ghost.h"
 #include "ollie_kate.h"
 
+#include <ktexteditor_version.h>
+#if KTEXTEDITOR_VERSION_MAJOR < 6
+#include <KTextEditor/InlineNoteInterface>
+#include <KTextEditor/CodeCompletionInterface>
+#include <KTextEditor/ConfigInterface>
+#endif
+
 #include <QDBusMessage>
 #include <QDBusPendingCall>
 #include <QDBusPendingReply>
@@ -96,7 +103,13 @@ OllieGhostProvider::OllieGhostProvider(KTextEditor::View *view, QDBusInterface *
     connect(view->document(), &KTextEditor::Document::textChanged,
             this, &OllieGhostProvider::onTextChanged);
 
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
     view->registerInlineNoteProvider(this);
+#else
+    auto *noteIface = qobject_cast<KTextEditor::InlineNoteInterface *>(view);
+    if (noteIface)
+        noteIface->registerInlineNoteProvider(this);
+#endif
 }
 
 OllieGhostProvider::~OllieGhostProvider()
@@ -104,12 +117,22 @@ OllieGhostProvider::~OllieGhostProvider()
     // m_overlay is parented to the view widget and may already be destroyed
     // by Qt's child cleanup before we get here — just null it out.
     m_overlay = nullptr;
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
     m_view->unregisterInlineNoteProvider(this);
+#else
+    auto *iface = qobject_cast<KTextEditor::InlineNoteInterface *>(m_view);
+    if (iface)
+        iface->unregisterInlineNoteProvider(this);
+#endif
 }
 
 // --- InlineNoteProvider interface ---
 
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
 QList<int> OllieGhostProvider::inlineNotes(int line) const
+#else
+QVector<int> OllieGhostProvider::inlineNotes(int line) const
+#endif
 {
     if (m_suggestionLines.isEmpty() || m_suggestionStartLine < 0)
         return {};
@@ -141,9 +164,14 @@ QSize OllieGhostProvider::inlineNoteSize(const KTextEditor::InlineNote &note) co
     return QSize(qRound(width), note.lineHeight());
 }
 
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
 void OllieGhostProvider::paintInlineNote(const KTextEditor::InlineNote &note, QPainter &painter, Qt::LayoutDirection direction) const
 {
     Q_UNUSED(direction);
+#else
+void OllieGhostProvider::paintInlineNote(const KTextEditor::InlineNote &note, QPainter &painter) const
+{
+#endif
 
     if (m_suggestionLines.isEmpty())
         return;
@@ -225,8 +253,14 @@ bool OllieGhostProvider::hasSuggestion() const
 void OllieGhostProvider::onCursorPositionChanged()
 {
     // Don't react to cursor changes while completion popup is active
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
     if (m_view->isCompletionActive())
         return;
+#else
+    auto *ccIface = qobject_cast<KTextEditor::CodeCompletionInterface *>(m_view);
+    if (ccIface && ccIface->isCompletionActive())
+        return;
+#endif
 
     if (hasSuggestion()) {
         KTextEditor::Cursor cur = m_view->cursorPosition();
@@ -342,7 +376,16 @@ void OllieGhostProvider::showOverlay()
     QStringList contLines = m_suggestionLines.mid(1);
 
     // Get font from the view's config
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
     QFont font = m_view->configValue(QStringLiteral("font")).value<QFont>();
+#else
+    QFont font;
+    auto *cfgIface = qobject_cast<KTextEditor::ConfigInterface *>(m_view);
+    if (cfgIface)
+        font = cfgIface->configValue(QStringLiteral("font")).value<QFont>();
+    else
+        font = m_view->font();
+#endif
     m_overlay->setLines(contLines, font);
 
     // Position the overlay below the cursor line
diff --git a/kate/ollie_ghost.h b/kate/ollie_ghost.h
index ca3051f..767a43a 100644
--- a/kate/ollie_ghost.h
+++ b/kate/ollie_ghost.h
@@ -5,6 +5,7 @@
 #include <KTextEditor/View>
 #include <KTextEditor/Document>
 #include <KTextEditor/Cursor>
+#include <ktexteditor_version.h>
 
 #include <QDBusInterface>
 #include <QTimer>
@@ -41,9 +42,17 @@ public:
     ~OllieGhostProvider() override;
 
     // InlineNoteProvider interface
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
     QList<int> inlineNotes(int line) const override;
+#else
+    QVector<int> inlineNotes(int line) const override;
+#endif
     QSize inlineNoteSize(const KTextEditor::InlineNote &note) const override;
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
     void paintInlineNote(const KTextEditor::InlineNote &note, QPainter &painter, Qt::LayoutDirection direction) const override;
+#else
+    void paintInlineNote(const KTextEditor::InlineNote &note, QPainter &painter) const override;
+#endif
 
     /// Accept the current suggestion (insert into document). Returns true if accepted.
     bool accept();
diff --git a/kate/ollie_kate.cpp b/kate/ollie_kate.cpp
index 7d80db7..f378592 100644
--- a/kate/ollie_kate.cpp
+++ b/kate/ollie_kate.cpp
@@ -5,6 +5,10 @@
 #include <QKeyEvent>
 #include <KTextEditor/Document>
 #include <KTextEditor/Editor>
+#include <ktexteditor_version.h>
+#if KTEXTEDITOR_VERSION_MAJOR < 6
+#include <KTextEditor/CodeCompletionInterface>
+#endif
 
 #include <QVBoxLayout>
 #include <QHBoxLayout>
@@ -740,9 +744,16 @@ bool OllieKateView::eventFilter(QObject *obj, QEvent *event)
         if (m_ghost->hasSuggestion()) {
             // Don't intercept keys while a popup or completion widget is active
             auto *activeView = m_mainWindow->activeView();
+#if KTEXTEDITOR_VERSION_MAJOR >= 6
             if (QApplication::activePopupWidget() ||
                 (activeView && activeView->isCompletionActive()))
                 return QObject::eventFilter(obj, event);
+#else
+            auto *ccIface = activeView ? qobject_cast<KTextEditor::CodeCompletionInterface *>(activeView) : nullptr;
+            if (QApplication::activePopupWidget() ||
+                (ccIface && ccIface->isCompletionActive()))
+                return QObject::eventFilter(obj, event);
+#endif
 
             if (keyEvent->key() == Qt::Key_Tab && keyEvent->modifiers() == Qt::NoModifier) {
                 if (m_ghost->accept()) {