1 files changed, 12 insertions, 0 deletions
diff --git a/src/qml/jsruntime/qv4persistent.cpp b/src/qml/jsruntime/qv4persistent.cpp
index f8bc28160e..79c372348f 100644
--- a/src/qml/jsruntime/qv4persistent.cpp
+++ b/src/qml/jsruntime/qv4persistent.cpp
@@ -302,6 +302,10 @@ PersistentValue &PersistentValue::operator=(const PersistentValue &other)
             return *this;
         val = other.engine()->memoryManager->m_persistentValues->allocate();
     }
+    if (!other.val) {
+        *val = Encode::undefined();
+        return *this;
+    }
 
     Q_ASSERT(engine() == other.engine());
 
@@ -316,6 +320,10 @@ PersistentValue &PersistentValue::operator=(const WeakValue &other)
             return *this;
         val = other.engine()->memoryManager->m_persistentValues->allocate();
     }
+    if (!other.valueRef()) {
+        *val = Encode::undefined();
+        return *this;
+    }
 
     Q_ASSERT(engine() == other.engine());
 
@@ -379,6 +387,10 @@ WeakValue &WeakValue::operator=(const WeakValue &other)
             return *this;
         allocVal(other.engine());
     }
+    if (!other.val) {
+        *val = Encode::undefined();
+        return *this;
+    }
 
     Q_ASSERT(engine() == other.engine());