diff --git a/src/db/db_access.h b/src/db/db_access.h
index d52e5fe17..90d242f5e 100644
--- a/src/db/db_access.h
+++ b/src/db/db_access.h
@@ -88,6 +88,8 @@
 #ifndef INCLdb_accessh
 #define INCLdb_accessh
 
+#include <stddef.h>
+
 #include <epicsTypes.h>
 #include <tsDefs.h>
 #include <callback.h>