diff --git a/src/db/dbScan.h b/src/db/dbScan.h
index 9d801fcd5..d87fba0ee 100644
--- a/src/db/dbScan.h
+++ b/src/db/dbScan.h
@@ -24,6 +24,8 @@ of this distribution.
 /*definitions for SCAN_IO_EVENT */
 typedef void * IOSCANPVT;
 
+struct dbCommon;
+
 epicsShareFunc long epicsShareAPI scanInit(void);
 epicsShareFunc void epicsShareAPI post_event(int event);
 epicsShareFunc void epicsShareAPI scanAdd(struct dbCommon *);