diff --git a/src/modules/readline/readlinemod.c b/src/modules/readline/readlinemod.c
index cb7418fd04d6239d56df5964bca8f287ede58088..841eee3aecf3b6b7647c4314ba7c622906a113f1 100644
--- a/src/modules/readline/readlinemod.c
+++ b/src/modules/readline/readlinemod.c
@@ -13,6 +13,8 @@
 #include "pike_macros.h"
 #include "threads.h"
 
+#include <errno.h>
+
 #ifndef HAVE_LIBTERMCAP
 #undef HAVE_LIBREADLINE
 #endif