diff --git a/include/orcus/json_document_tree.hpp b/include/orcus/json_document_tree.hpp
index e558c38cbcdc22fc5054b76ea429435167aeb32e..9942ed8d4260230551ff1ed4d3eb7a9341cc3f37 100644
--- a/include/orcus/json_document_tree.hpp
+++ b/include/orcus/json_document_tree.hpp
@@ -14,6 +14,7 @@
 #include <string>
 #include <memory>
 #include <vector>
+#include <cstdint>
 
 namespace orcus {
 
diff --git a/include/orcus/sax_parser.hpp b/include/orcus/sax_parser.hpp
index f7283d24dae8a4033fd642ab064aa8ecd5faddba..5f42e2f091bcc26438c0a80fa014d79a8bda15c1 100644
--- a/include/orcus/sax_parser.hpp
+++ b/include/orcus/sax_parser.hpp
@@ -11,6 +11,7 @@
 #include "sax_parser_base.hpp"
 
 #include <string_view>
+#include <cstdint>
 
 namespace orcus {
 
diff --git a/include/orcus/yaml_document_tree.hpp b/include/orcus/yaml_document_tree.hpp
index d22a588db0d507cb4bbb0a5b98985d63d6d45923..886881fe058e3ef530103b5d27b851822c1c4c28 100644
--- a/include/orcus/yaml_document_tree.hpp
+++ b/include/orcus/yaml_document_tree.hpp
@@ -14,6 +14,7 @@
 #include <string>
 #include <memory>
 #include <vector>
+#include <cstdint>
 
 namespace orcus {
 
diff --git a/include/orcus/zip_archive.hpp b/include/orcus/zip_archive.hpp
index afc6727853c42f5415fcceea276b1d9df708102d..aac5e4bc65a7a1cb9a3344cc7d8caa0615229c99 100644
--- a/include/orcus/zip_archive.hpp
+++ b/include/orcus/zip_archive.hpp
@@ -15,6 +15,7 @@
 #include <vector>
 #include <memory>
 #include <ostream>
+#include <cstdint>
 
 namespace orcus {