diff --git a/c/hdt4pl.cpp b/c/hdt4pl.cpp
index a8bd509..3b0ed70 100644
--- a/c/hdt4pl.cpp
+++ b/c/hdt4pl.cpp
@@ -215,6 +215,7 @@ PREDICATE(hdt_open, 3)
   int indexed = TRUE;
   PlTail options(A3);
   PlTerm opt;
+  char *name;
 
   while(options.next(opt))
   { atom_t name;
@@ -234,15 +235,18 @@ PREDICATE(hdt_open, 3)
       return PL_type_error("option", opt);
   }
 
+  if ( !PL_get_file_name(A2, &name, PL_FILE_EXIST) )
+    return FALSE;
+
   try
   { if ( access == ATOM_map )
     { if ( indexed )
-	hdt = HDTManager::mapIndexedHDT(A2);
+	hdt = HDTManager::mapIndexedHDT(name);
       else
 	hdt = HDTManager::mapHDT(A2);
     } else if ( access == ATOM_load )
     { if ( indexed )
-	hdt = HDTManager::loadIndexedHDT(A2);
+	hdt = HDTManager::loadIndexedHDT(name);
       else
 	hdt = HDTManager::loadHDT(A2);
     } else
@@ -752,7 +756,7 @@ PREDICATE(hdt_search_cost_id, 5)
   try
   { TripleID t(s,p,o);
     IteratorTripleID *it = symb->hdt->getTriples()->search(t);
-    int numResults = it->estimatedNumResults();
+    long numResults = it->estimatedNumResults();
     delete it;
     return (A5 = numResults);
   } CATCH_HDT;
diff --git a/prolog/hdt.pl b/prolog/hdt.pl
index 1d1b4b2..d6135b4 100644
--- a/prolog/hdt.pl
+++ b/prolog/hdt.pl
@@ -350,13 +350,14 @@
 %
 %	True if a triple with the indicated identifiers exists.
 
-%%	hdt_search_cost(HDT, ?S, ?P, ?O, -Cost:float) is det.
+%%	hdt_search_cost(HDT, ?S, ?P, ?O, -Cost:nonneg) is det.
 
 hdt_search_cost(HDT, S, P, O, Cost) :-
 	Triple   = t(S,P,O),
 	TripleID = t(SID,PID,OID),
 	hdt_pre_triple(HDT, Triple, TripleID),
-	hdt_search_cost_id(HDT, SID, PID, OID, Cost).
+	hdt_search_cost_id(HDT, SID, PID, OID, Cost), !.
+hdt_search_cost(_, _, _, _, 0).
 
 
 		 /*******************************