diff --git a/code/ATMOSPHERICS/_atmos_setup.dm b/code/ATMOSPHERICS/_atmos_setup.dm
index 14efbb7de1..47903bfdc6 100644
--- a/code/ATMOSPHERICS/_atmos_setup.dm
+++ b/code/ATMOSPHERICS/_atmos_setup.dm
@@ -17,6 +17,7 @@
 #define CONNECT_TYPE_REGULAR	1
 #define CONNECT_TYPE_SUPPLY		2
 #define CONNECT_TYPE_SCRUBBER	4
+#define CONNECT_TYPE_HE			8
 
 var/global/list/pipe_colors = list("grey" = PIPE_COLOR_GREY, "red" = PIPE_COLOR_RED, "blue" = PIPE_COLOR_BLUE, "cyan" = PIPE_COLOR_CYAN, "green" = PIPE_COLOR_GREEN, "yellow" = PIPE_COLOR_YELLOW, "purple" = PIPE_COLOR_PURPLE)