--- mpartition.c
+++ mpartition.c
@@ -514,7 +514,7 @@ void mpartition(int argc, char **argv, i
 			read(fd, (char *) buf, 512);
 		}
 		memset((char *)(partTable+1), 0, 4*sizeof(*partTable));
-		set_dword(((unsigned char*)buf)+510, 0xaa55);
+		set_word(((unsigned char*)buf)+510, 0xaa55);
 	}
 
 	/* check for boot signature, and place it if needed */