1 files changed, 7 insertions, 1 deletions
diff --git a/src/lmm.h b/src/lmm.h
index f4f49aa..8a65f8d 100644
--- a/src/lmm.h
+++ b/src/lmm.h
@@ -45,10 +45,16 @@ public:
   size_t e_mode;
 };
 
+
+constexpr uint8_t CHR_X = 'X';
+constexpr uint8_t CHR_Y = 'Y';
+constexpr uint8_t CHR_M = 'M';
+
 // typedef tuple< string, uint16_t, uint32_t, uint32_t > MarkerInfo; // name, chr, pos, line
 struct MarkerInfo {
   string name;
-  size_t chr, pos, line_no, n_miss;
+  uint8_t chr;
+  size_t pos, line_no, n_miss;
   double maf;
 } ;