diff --git a/include/grmNeighborhood.h b/include/grmNeighborhood.h
index ae7c44e1d6d26d98556a72ad45c8ffff3409b4fc..1d68f2c10228e88d8d65801b4123d7885d5d0a72 100644
--- a/include/grmNeighborhood.h
+++ b/include/grmNeighborhood.h
@@ -23,7 +23,7 @@
 #if defined(_WIN32)
 typedef __int64 NeighIDType;
 #else
-typedef long unsigned int NeighIDType;
+typedef long int NeighIDType;
 #endif
 
 enum CONNECTIVITY{FOUR = 0, EIGHT};