diff --git a/docs/libcurl/opts/CURLOPT_RTSP_TRANSPORT.md b/docs/libcurl/opts/CURLOPT_RTSP_TRANSPORT.md
index 221f2d1af6..42b8017081 100644
--- a/docs/libcurl/opts/CURLOPT_RTSP_TRANSPORT.md
+++ b/docs/libcurl/opts/CURLOPT_RTSP_TRANSPORT.md
@@ -59,6 +59,11 @@ int main(void)
 }
 ~~~
 
+# HISTORY
+
+CURL_RTSPREQ_\* enums became `long` types in 8.13.0, prior to this version
+a `long` cast is necessary when passing to curl_easy_setopt(3).
+
 # %AVAILABILITY%
 
 # RETURN VALUE