diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index a779c23..160cee4 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -19,7 +19,7 @@
 #include <qpdf/QPDF_Null.hh>
 #include <qpdf/QPDF_Dictionary.hh>
 
-std::string QPDF::qpdf_version = "4.0.0";
+std::string QPDF::qpdf_version = "4.0.0+";
 
 static char const* EMPTY_PDF =
     "%PDF-1.3\n"