diff --git a/src/ssl_crtlist.c b/src/ssl_crtlist.c
index b60f452d7..25d84457f 100644
--- a/src/ssl_crtlist.c
+++ b/src/ssl_crtlist.c
@@ -9,6 +9,7 @@
  *
  */
 
+#include <errno.h>
 #include <stdlib.h>
 #include <string.h>
 #include <sys/stat.h>