diff --git a/src/shuffle.h b/src/shuffle.h
index 4c1e208e..137651e5 100644
--- a/src/shuffle.h
+++ b/src/shuffle.h
@@ -3,6 +3,11 @@
 
 #include <stdlib.h>
 #include <stdbool.h>
+#include <stdint.h>
+
+#define CHUNK_SIZE_MB UINT64_C(1024) * UINT64_C(1024)
+#define CHUNK_SIZE_GB UINT64_C(1024) * (CHUNK_SIZE_MB)
+#define DEFAULT_SHUFFLE_CHUNK_SIZE UINT64_C(2) * (CHUNK_SIZE_GB)
 
 bool shuffle_file(char *filename);
 bool shuffle_file_chunked(char *filename, size_t parts);