Index: code/unix/sdl_glimp.c
===================================================================
--- code/unix/sdl_glimp.c       (revision 819)
+++ code/unix/sdl_glimp.c       (working copy)
@@ -650,6 +650,7 @@
         tstencilbits = 0;
     }

+    sdlcolorbits = 4;
     if (tcolorbits == 24)
         sdlcolorbits = 8;