diff --git a/core/state/reader.go b/core/state/reader.go
index 93083c8ae2..0f51949943 100644
--- a/core/state/reader.go
+++ b/core/state/reader.go
@@ -147,7 +147,9 @@ func (r *cachingCodeReader) CodeSize(addr common.Address, codeHash common.Hash)
 	if err != nil {
 		return 0, err
 	}
-	return len(code), nil
+	n := len(code)
+	r.codeSizeCache.Add(codeHash, n)
+	return n, nil
 }
 
 // flatReader wraps a database state reader and is safe for concurrent access.