--- a/include/QtCrypto/qca_core.h
+++ b/include/QtCrypto/qca_core.h
@@ -43,6 +43,7 @@
 #include <QSharedDataPointer>
 #include <QString>
 #include <QStringList>
+#include <QIODevice>
 
 /**
    The current version of %QCA.