diff --git a/BUILD.gn b/BUILD.gn
index 5bcb9cb..8bfe0ca55 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -122,6 +122,7 @@
     "public/fpdf_progressive.h",
     "public/fpdf_save.h",
     "public/fpdf_searchex.h",
+    "public/fpdf_signature.h",
     "public/fpdf_structtree.h",
     "public/fpdf_sysfontinfo.h",
     "public/fpdf_text.h",