diff --git a/game/gametypes.h b/game/gametypes.h
index 47dd9ab..903ac9a 100644
--- a/game/gametypes.h
+++ b/game/gametypes.h
@@ -1,6 +1,8 @@
 #ifndef _GAME_TYPES_H_
 #define _GAME_TYPES_H_
 
+#include <limits>       // std::numeric_limits
+
 // Type for a team IDs
 typedef unsigned short team_id_t;
 
@@ -16,4 +18,11 @@ typedef char unitType_c;
 // Typedef for unit visual representations
 typedef char unitVis_c;
 
+// Invalid data for above types
+static const team_id_t 		team_id_invalid 	= std::numeric_limits<team_id_t>::max();
+static const player_id_t 	player_id_invalid 	= std::numeric_limits<player_id_t>::max();
+static const unit_id_t 		unit_id_invalid 	= std::numeric_limits<unit_id_t>::max();
+static const unitType_c 	unitType_invalid 	= std::numeric_limits<unitType_c>::max();
+static const unitVis_c 		unitVis_invalid 	= std::numeric_limits<unitVis_c>::max();
+
 #endif //_GAME_TYPES_H_
\ No newline at end of file
diff --git a/maths/mathtypes.h b/maths/mathtypes.h
index 8dfdd5f..ab1e0eb 100644
--- a/maths/mathtypes.h
+++ b/maths/mathtypes.h
@@ -1,10 +1,16 @@
 #ifndef _BASETYPES_H_
 #define _BASETYPES_H_
 
+#include <limits>       // std::numeric_limits
+
 // Coordinate types
 typedef short 			coord_t;
 typedef unsigned short 	ucoord_t;
 
+// Invalid values
+static const coord_t 		coord_invalid 	= std::numeric_limits<coord_t>::max();
+static const ucoord_t 		ucoord_invalid 	= std::numeric_limits<ucoord_t>::max();
+
 // Direction representation
 enum dir_t : char
 {