diff --git a/third_party/pdfium/core/fxcodec/jpx/cjpx_decoder.cpp b/third_party/pdfium/core/fxcodec/jpx/cjpx_decoder.cpp
index c66985a7f..83a9ba132 100644
--- a/third_party/pdfium/core/fxcodec/jpx/cjpx_decoder.cpp
+++ b/third_party/pdfium/core/fxcodec/jpx/cjpx_decoder.cpp
@@ -6,6 +6,7 @@
 
 #include "core/fxcodec/jpx/cjpx_decoder.h"
 
+#include <cstring>
 #include <algorithm>
 #include <limits>
 #include <utility>