diff --git a/fpdfsdk/cpdfsdk_interform.cpp b/fpdfsdk/cpdfsdk_interform.cpp
index b7b7109..bd3c7fa 100644
--- a/fpdfsdk/cpdfsdk_interform.cpp
+++ b/fpdfsdk/cpdfsdk_interform.cpp
@@ -35,6 +35,7 @@
 #include "fpdfsdk/ipdfsdk_annothandler.h"
 #include "fxjs/ijs_event_context.h"
 #include "fxjs/ijs_runtime.h"
+#include "third_party/base/ptr_util.h"
 #include "third_party/base/stl_util.h"
 
 #ifdef PDF_ENABLE_XFA