diff --git a/src/keys/CompositeKey.cpp b/src/keys/CompositeKey.cpp
index afd8f0704..d3c807bf3 100644
--- a/src/keys/CompositeKey.cpp
+++ b/src/keys/CompositeKey.cpp
@@ -51,6 +51,11 @@ CompositeKey* CompositeKey::clone() const
 
 CompositeKey& CompositeKey::operator=(const CompositeKey& key)
 {
+    // handle self assignment as that would break when calling clear()
+    if (this == &key) {
+        return *this;
+    }
+
     clear();
 
     Q_FOREACH (const Key* subKey, key.m_keys) {
diff --git a/tests/TestKeys.cpp b/tests/TestKeys.cpp
index 38bb0707d..51d09495e 100644
--- a/tests/TestKeys.cpp
+++ b/tests/TestKeys.cpp
@@ -70,6 +70,10 @@ void TestKeys::testComposite()
     *compositeKey4 = *compositeKey3;
     QCOMPARE(compositeKey3->rawKey(), compositeKey4->rawKey());
 
+    // test self-assignment
+    *compositeKey3 = *compositeKey3;
+    QCOMPARE(compositeKey3->rawKey(), compositeKey4->rawKey());
+
     delete compositeKey3;
     delete compositeKey4;
 }