--- src/lib/EBOOKDocument.cpp
+++ src/lib/EBOOKDocument.cpp
@@ -147,11 +147,11 @@
         {
           const char *const name = char_cast(xmlTextReaderConstLocalName(reader.get()));
           const char *const uri = char_cast(xmlTextReaderConstNamespaceUri(reader.get()));
-          if ((EBOOKHTMLToken::html | EBOOKHTMLToken::NS_html) == getHTMLTokenId(name, uri))
+          if ((+EBOOKHTMLToken::html | EBOOKHTMLToken::NS_html) == getHTMLTokenId(name, uri))
             type = EBOOKDocument::TYPE_XHTML;
-          else if ((EPubToken::container | EPubToken::NS_container) == getEPubTokenId(name, uri))
+          else if ((+EPubToken::container | EPubToken::NS_container) == getEPubTokenId(name, uri))
             type = EBOOKDocument::TYPE_EPUB;
-          else if ((EBOOKOPFToken::package | EBOOKOPFToken::NS_opf) == getOPFTokenId(name, uri))
+          else if ((+EBOOKOPFToken::package | EBOOKOPFToken::NS_opf) == getOPFTokenId(name, uri))
             type = EBOOKDocument::TYPE_EPUB;
           else if (EBOOKOPFToken::package == getOPFTokenId(name, uri))
             type = EBOOKDocument::TYPE_OPENEBOOK;