diff --git a/D1Image.bt b/D1Image.bt
index b0cabaf7093b8e629c3c2dd01039974d0cc98e9f..c8ed7985b96a5bb0107eab39fc5dffc20f58baab 100644
--- a/D1Image.bt
+++ b/D1Image.bt
@@ -38,6 +38,19 @@ if (correct_magic != head.magic) {
     Warning("wrong magic!");
 }  
 
+local uint32 tmp_check_num = 0;
+local uint64 i;
+for(i = 10h; i<FileSize(); i+=4){
+    tmp_check_num += ReadUInt(i);
+}
+tmp_check_num += ReadUInt(0);
+tmp_check_num += ReadUInt(4);
+tmp_check_num += ReadUInt(8);
+tmp_check_num += 0x5F0A6C39; // stamp number
+if (tmp_check_num != ReadUInt(0xC)) {
+    Warning("Wrong check_num!");
+}
+
 local uint32 opcode = head.jump_instruction & 0x7f;
 // 0x6f JAL opcode 
 if (opcode == 0x6f)