diff --git a/src/libcharon/plugins/error_notify/error_notify.c b/src/libcharon/plugins/error_notify/error_notify.c
index 6e6dea55f..2a65ad5a2 100644
--- a/src/libcharon/plugins/error_notify/error_notify.c
+++ b/src/libcharon/plugins/error_notify/error_notify.c
@@ -19,6 +19,7 @@
 #include <stdio.h>
 #include <stdlib.h>
 #include <stddef.h>
+#include <string.h>
 #include <unistd.h>
 #include <sys/stat.h>
 #include <sys/socket.h>