Index: src/game/g_trigger.c
===================================================================
--- src/game/g_trigger.c	(revision 793)
+++ src/game/g_trigger.c	(working copy)
@@ -1043,6 +1043,12 @@
   if( self->timestamp > level.time )
     return;
 
+  if( self->damage <= 0 )
+  {
+    G_Printf( S_COLOR_YELLOW "WARNING: trigger_heal has negative value\n" );
+    return;
+  }
+
   if( self->spawnflags & 2 )
     self->timestamp = level.time + 1000;
   else