diff --git a/lib/multi_ev.c b/lib/multi_ev.c
index 7ea3b2827e..0da5b0e904 100644
--- a/lib/multi_ev.c
+++ b/lib/multi_ev.c
@@ -40,7 +40,9 @@ static void mev_in_callback(struct Curl_multi *multi, bool value)
   multi->in_callback = value;
 }
 
+#ifdef DEBUGBUILD
 #define SH_ENTRY_MAGIC 0x570091d
+#endif
 
 /* Information about a socket for which we inform the libcurl application
  * what to supervise (CURL_POLL_IN/CURL_POLL_OUT/CURL_POLL_REMOVE)