diff --git a/src/hb-open-type.hh b/src/hb-open-type.hh
index 2991d8e752dbeebcc39f58441e577e756bbbdf07..e235a97c320a705d90220f650b02ceb822fa9200 100644
--- a/src/hb-open-type.hh
+++ b/src/hb-open-type.hh
@@ -146,7 +146,7 @@ struct LONGDATETIME
  * system, feature, or baseline */
 struct Tag : HBUINT32
 {
-  Tag& operator = (uint32_t i) { HBUINT32::operator= (i); return *this; }
+  Tag& operator = (hb_tag_t i) { HBUINT32::operator= (i); return *this; }
   /* What the char* converters return is NOT nul-terminated.  Print using "%.4s" */
   operator const char* () const { return reinterpret_cast<const char *> (&this->v); }
   operator char* ()             { return reinterpret_cast<char *> (&this->v); }