diff --git a/src/validation.h b/src/validation.h
index e86b3d3af8c..fc7add85b7d 100644
--- a/src/validation.h
+++ b/src/validation.h
@@ -40,7 +40,7 @@ class CBlockIndex;
 class CBlockTreeDB;
 class CBlockUndo;
 class CChainParams;
-class CCheckpointData;
+struct CCheckpointData;
 class CInv;
 class CConnman;
 class CScriptCheck;