diff --git a/libqpdf/QPDF.cc b/libqpdf/QPDF.cc
index f031eb5..4c9296e 100644
--- a/libqpdf/QPDF.cc
+++ b/libqpdf/QPDF.cc
@@ -196,6 +196,7 @@ QPDF::EncryptionParameters::EncryptionParameters() :
 
 QPDF::Members::Members() :
     unique_id(0),
+    file(new InvalidInputSource()),
     provided_password_is_hex_key(false),
     ignore_xref_streams(false),
     suppress_warnings(false),