diff --git a/Changelog b/Changelog
index 87afc93..6bacf4a 100644
--- a/Changelog
+++ b/Changelog
@@ -1,5 +1,8 @@
 [Changes 1.2c01]
 
+* Fix off-by-one error in add_socketread() and set_socketwrite() found
+  by Coverity. (caf)
+
 * Fix longstanding bug with ordering of rfc1459[] array. (caf)
 
 * Fix crash after /SETAR -, reported by riderplus. (caf)
diff --git a/source/misc.c b/source/misc.c
index 81e2a08..5ad8f9a 100644
--- a/source/misc.c
+++ b/source/misc.c
@@ -3513,7 +3513,7 @@ int BX_add_socketread(int s, int port, unsigned long flags, char *server, void (
 		FD_ZERO(&rd);
 		set_socket_read(&rd, &rd);
 	}
-	if (s > FD_SETSIZE)
+	if (s >= FD_SETSIZE)
 		return -1;
 	if (s > sock_manager.max_fd)
 		sock_manager.max_fd = s;
@@ -3531,7 +3531,7 @@ int BX_add_socketread(int s, int port, unsigned long flags, char *server, void (
 
 int BX_set_socketwrite(int s)
 {
-	if (s > FD_SETSIZE)
+	if (s >= FD_SETSIZE)
 		return -1;
 	if (s > sock_manager.max_fd)
 		sock_manager.max_fd = s;