diff --git a/libqpdf/qpdf/Pipeline_private.hh b/libqpdf/qpdf/Pipeline_private.hh
index c46af4c..084bf4e 100644
--- a/libqpdf/qpdf/Pipeline_private.hh
+++ b/libqpdf/qpdf/Pipeline_private.hh
@@ -4,6 +4,7 @@
 #include <qpdf/Pipeline.hh>
 
 #include <qpdf/Pl_Flate.hh>
+#include <qpdf/Types.h>
 
 namespace qpdf::pl
 {