diff --git a/include/woff2/output.h b/include/woff2/output.h
index dc78ccf..9e85007 100644
--- a/include/woff2/output.h
+++ b/include/woff2/output.h
@@ -11,6 +11,7 @@
 
 #include <algorithm>
 #include <cstring>
+#include <cstdint>
 #include <memory>
 #include <string>