diff --git a/eeschema/dialogs/dialog_sheet_properties.cpp b/eeschema/dialogs/dialog_sheet_properties.cpp
index 66fcdeb25c..aff7e3d5ca 100644
--- a/eeschema/dialogs/dialog_sheet_properties.cpp
+++ b/eeschema/dialogs/dialog_sheet_properties.cpp
@@ -167,7 +167,7 @@ bool DIALOG_SHEET_PROPERTIES::TransferDataToWindow()
     wxString nextPageNumber;
 
     if( m_sheet->IsNew() )
-        nextPageNumber.Printf( "%z", hierarchy.size() + 1 );
+        nextPageNumber.Printf( "%d", static_cast<int>( hierarchy.size() ) + 1 );
     else
         nextPageNumber = m_sheet->GetPageNumber( instance );