--- a/src/suffer.cpp
+++ b/src/suffer.cpp
@@ -118,6 +118,8 @@
 static const trait_id trait_FRESHWATEROSMOSIS( "FRESHWATEROSMOSIS" );
 static const trait_id trait_GILLS( "GILLS" );
 static const trait_id trait_GILLS_CEPH( "GILLS_CEPH" );
+static const trait_id trait_THRESH_GYNOID( "THRESH_GYNOID" );
+static const trait_id trait_THRESH_VAMP( "THRESH_VAMP" );
 static const trait_id trait_JITTERY( "JITTERY" );
 static const trait_id trait_KILLER( "KILLER" );
 static const trait_id trait_LEAVES( "LEAVES" );
@@ -245,7 +247,8 @@
 
 void Character::suffer_while_underwater()
 {
-    if( !has_trait( trait_GILLS ) && !has_trait( trait_GILLS_CEPH ) ) {
+    if( !has_trait( trait_GILLS ) && !has_trait( trait_GILLS_CEPH ) &&
+        !has_trait( trait_THRESH_GYNOID ) && !has_trait( trait_THRESH_VAMP ) ) {
         oxygen--;
     }
     if( oxygen < 12 && worn_with_flag( "REBREATHER" ) ) {