diff --git a/src/lib/CMakeLists.txt b/src/lib/CMakeLists.txt
--- a/src/lib/CMakeLists.txt
+++ b/src/lib/CMakeLists.txt
@@ -40,6 +40,7 @@
     HEADER_NAMES
         AbstractHighlighter
         Definition
+        DefinitionDownloader
         FoldingRegion
         Format
         Repository