diff --git a/modules/stream_out/rtp.h b/modules/stream_out/rtp.h
index eae375486fb61146c51d5ad449a6e865070def15..a4883665df0db4c9d2f85b28140f9ae0e1e964b0 100644
--- a/modules/stream_out/rtp.h
+++ b/modules/stream_out/rtp.h
@@ -77,7 +77,7 @@ typedef struct rtp_format_t
     uint8_t      payload_type;
     unsigned     clock_rate;
     unsigned     channels;
-    int          cat;
+    enum es_format_category_e cat;
     /* Used in SDP only */
     unsigned     bitrate;
     const char  *ptname;