+ small fix

src/zimlib/include/zim/fileiterator.h

@@ -67,8 +67,8 @@ namespace zim
       const_iterator operator++(int)
       {
         const_iterator it = *this;
-        ++it;
+        operator++();
-        return *this;
+        return it;
       }
 
       const_iterator& operator--()
@@ -78,11 +78,11 @@ namespace zim
         return *this;
       }
 
-      const_iterator& operator--(int)
+      const_iterator operator--(int)
       {
         const_iterator it = *this;
-        --it;
+        operator--();
-        return *this;
+        return it;
       }
 
       const Article& operator*() const