diff --git a/src/vim.h b/src/vim.h
index 5067c5a..49fb870 100644
--- a/src/vim.h
+++ b/src/vim.h
@@ -505,6 +505,9 @@
 #endif
 #include <stdarg.h>
 
+/* for offsetof() */
+#include <stddef.h>
+
 #if defined(HAVE_SYS_SELECT_H) && \
 	(!defined(HAVE_SYS_TIME_H) || defined(SYS_SELECT_WITH_SYS_TIME))
 # include <sys/select.h>