diff --git a/include/rapidjson/schema.h b/include/rapidjson/schema.h
index 4c1eacbbf..b182aa27f 100644
--- a/include/rapidjson/schema.h
+++ b/include/rapidjson/schema.h
@@ -1338,7 +1338,7 @@ class GenericSchemaDocument {
         \param remoteProvider An optional remote schema document provider for resolving remote reference. Can be null.
         \param allocator An optional allocator instance for allocating memory. Can be null.
     */
-    GenericSchemaDocument(const ValueType& document, IRemoteSchemaDocumentProviderType* remoteProvider = 0, Allocator* allocator = 0) :
+    explicit GenericSchemaDocument(const ValueType& document, IRemoteSchemaDocumentProviderType* remoteProvider = 0, Allocator* allocator = 0) :
         remoteProvider_(remoteProvider),
         allocator_(allocator),
         ownAllocator_(),