diff --git a/src/haproxy.c b/src/haproxy.c
index 1060fbc05..3f0e097bf 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -210,7 +210,6 @@ struct global global = {
 #endif
 	/* by default allow clients which use a privileged port for TCP only */
 	.clt_privileged_ports = HA_PROTO_TCP,
-	.maxthrpertgroup = DEF_MAX_THREADS_PER_GROUP,
 	/* others NULL OK */
 };
 
diff --git a/src/thread.c b/src/thread.c
index bb733a602..94b7b8dd7 100644
--- a/src/thread.c
+++ b/src/thread.c
@@ -1682,8 +1682,17 @@ void thread_detect_count(void)
 	if (global.nbtgroups) {
 		grp_min = grp_max = global.nbtgroups;
 		/* ignore max-threads-per-group if thread-groups is configured */
+		if (global.maxthrpertgroup)
+			ha_notice("max-threads-per-group is used to automatically calculate the optimal number of thread groups. It is ignored when thread-groups is set.\n");
 		global.maxthrpertgroup = MAX_THREADS_PER_GROUP;
 	}
+	else {
+		/* set the default max-threads-per-group to calculate the
+		 * optimal number of groups.
+		 */
+		if (!global.maxthrpertgroup)
+			global.maxthrpertgroup = DEF_MAX_THREADS_PER_GROUP;
+	}
 
 #if defined(USE_THREAD)
 	/* Adjust to boot settings if not forced */