diff --git a/lib/grape.g b/lib/grape.g
index 683abb6..3f5fdf0 100644
--- a/lib/grape.g
+++ b/lib/grape.g
@@ -39,13 +39,12 @@ GRAPE_RANDOM := false; # Determines if certain random methods are to be used
 GRAPE_NRANGENS := 18;  # The number of random generators taken for a subgroup
 		       # when  GRAPE_RANDOM=true.
 
-GRAPE_NAUTY := true;   # Use nauty when true, else use bliss.
+GRAPE_NAUTY := @nauty@;   # Use nauty when true, else use bliss.
 
-GRAPE_DREADNAUT_EXE := 
-   ExternalFilename(DirectoriesPackagePrograms("grape"),"dreadnaut"); 
+GRAPE_DREADNAUT_EXE := "@GENTOO_PORTAGE_EPREFIX@/usr/bin/dreadnaut";
    # filename of dreadnaut or dreadnautB executable
 
-GRAPE_BLISS_EXE := ExternalFilename(DirectoriesSystemPrograms(),"bliss"); 
+GRAPE_BLISS_EXE := "@GENTOO_PORTAGE_EPREFIX@/usr/bin/bliss";
    # filename of bliss executable
 
 GRAPE_DREADNAUT_INPUT_USE_STRING := false;