diff --git a/src/db.h b/src/db.h
index 717462ff4..393978633 100644
--- a/src/db.h
+++ b/src/db.h
@@ -23,8 +23,6 @@
 class CDiskBlockIndex;
 class COutPoint;
 
-struct CBlockLocator;
-
 extern unsigned int nWalletDBUpdated;
 
 void ThreadFlushWalletDB(const std::string& strWalletFile);
diff --git a/src/primitives/block.h b/src/primitives/block.h
index 53fcd104a..d77ab162e 100644
--- a/src/primitives/block.h
+++ b/src/primitives/block.h
@@ -162,7 +162,7 @@ struct CBlockLocator
         vHave.clear();
     }
 
-    bool IsNull()
+    bool IsNull() const
     {
         return vHave.empty();
     }