diff --git a/src/lib/abstracthighlighter.cpp b/src/lib/abstracthighlighter.cpp
--- a/src/lib/abstracthighlighter.cpp
+++ b/src/lib/abstracthighlighter.cpp
@@ -119,7 +119,6 @@
     // verify definition, deal with no highlighting being enabled
     d->ensureDefinitionLoaded();
     if (!d->m_definition.isValid()) {
-        applyFormat(0, text.size(), Format());
         return State();
     }
 
@@ -133,6 +132,9 @@
         stateData->clear();
     }
     if (stateData->isEmpty()) {
+        if (!defData->isLoaded()) {
+            return State();
+        }
         stateData->push(defData->initialContext(), QStringList());
         stateData->m_defRef = currentDefRef;
     }
diff --git a/src/lib/definition.cpp b/src/lib/definition.cpp
--- a/src/lib/definition.cpp
+++ b/src/lib/definition.cpp
@@ -320,8 +320,11 @@
 
 Context* DefinitionData::initialContext() const
 {
-    Q_ASSERT(!contexts.isEmpty());
-    return contexts.first();
+    Context* c = nullptr;
+    if (!contexts.isEmpty()) {
+        c = contexts.first();
+    }
+    return c;
 }
 
 Context* DefinitionData::contextByName(const QString& wantedName) const