diff --git a/src/jobs.hpp b/src/jobs.hpp
index b881589..2c23728 100644
--- a/src/jobs.hpp
+++ b/src/jobs.hpp
@@ -33,7 +33,7 @@ class KggTask {
 
         std::ifstream kgg_stream_in(kgg_path_, std::ios::binary);
         char header[0x100]{};
-        kgg_stream_in.read(header, sizeof(kgg_stream_in));
+        kgg_stream_in.read(header, sizeof(header));
         if (std::equal(kMagicHeader.cbegin(), kMagicHeader.cend(), header)) {
             warning(L"invalid kgg header");
             return;