diff --git a/project.cbp b/project.cbp
index d2acb59..7a5b597 100644
--- a/project.cbp
+++ b/project.cbp
@@ -36,6 +36,9 @@
 		<Unit filename="histogram.h">
 			<Option target="&lt;{~None~}&gt;" />
 		</Unit>
+		<Unit filename="histogram_internal.h">
+			<Option target="&lt;{~None~}&gt;" />
+		</Unit>
 		<Unit filename="main.cpp" />
 		<Unit filename="text.cpp" />
 		<Unit filename="text.h">