diff --git a/src/plugins/plugin.c b/src/plugins/plugin.c
index 1b7b0a618..79bf76039 100644
--- a/src/plugins/plugin.c
+++ b/src/plugins/plugin.c
@@ -27,6 +27,7 @@
 
 #include <errno.h>
 #include <stdlib.h>
+#include <stddef.h>
 #include <unistd.h>
 #include <libgen.h>
 #include <stdarg.h>