diff --git a/test/unittest/schematest.cpp b/test/unittest/schematest.cpp
index 57af04a..db18065 100644
--- a/test/unittest/schematest.cpp
+++ b/test/unittest/schematest.cpp
@@ -849,6 +849,7 @@ public:
 
 private:
     RemoteSchemaDocumentProvider(const RemoteSchemaDocumentProvider&);
+    RemoteSchemaDocumentProvider& operator=(const RemoteSchemaDocumentProvider&);
 
     static const size_t kCount = 4;
     Document* d_[kCount];