diff --git a/src/addrdb.h b/src/addrdb.h
index 3ffcfe3e1..d8c66d872 100644
--- a/src/addrdb.h
+++ b/src/addrdb.h
@@ -14,6 +14,7 @@
 
 class CSubNet;
 class CAddrMan;
+class CDataStream;
 
 typedef enum BanReason
 {