diff --git a/include/SWI-Prolog.h b/include/SWI-Prolog.h
index cc6a9aabb..6f8007786 100755
--- a/include/SWI-Prolog.h
+++ b/include/SWI-Prolog.h
@@ -341,22 +341,22 @@ extern X_API atom_t PL_functor_name(functor_t);
 extern X_API int PL_functor_arity(functor_t);
 /* end PL_new_* functions =============================*/
 /* begin PL_put_* functions =============================*/
-extern X_API void PL_cons_functor(term_t, functor_t,...);
-extern X_API void PL_cons_functor_v(term_t, functor_t,term_t);
-extern X_API void PL_cons_list(term_t, term_t, term_t);
-extern X_API void PL_put_atom(term_t, atom_t);
-extern X_API void PL_put_atom_chars(term_t, const char *);
-extern X_API void PL_put_float(term_t, double);
-extern X_API void PL_put_functor(term_t, functor_t t);
-extern X_API void PL_put_int64(term_t, int64_t);
-extern X_API void PL_put_integer(term_t, long);
-extern X_API void PL_put_list(term_t);
-extern X_API void PL_put_list_chars(term_t, const char *);
+extern X_API int PL_cons_functor(term_t, functor_t,...);
+extern X_API int PL_cons_functor_v(term_t, functor_t,term_t);
+extern X_API int PL_cons_list(term_t, term_t, term_t);
+extern X_API int PL_put_atom(term_t, atom_t);
+extern X_API int PL_put_atom_chars(term_t, const char *);
+extern X_API int PL_put_float(term_t, double);
+extern X_API int PL_put_functor(term_t, functor_t t);
+extern X_API int PL_put_int64(term_t, int64_t);
+extern X_API int PL_put_integer(term_t, long);
+extern X_API int PL_put_list(term_t);
+extern X_API int PL_put_list_chars(term_t, const char *);
 extern X_API void PL_put_nil(term_t);
-extern X_API void PL_put_pointer(term_t, void *);
-extern X_API void PL_put_string_chars(term_t, const char *);
-extern X_API void PL_put_term(term_t, term_t);
-extern X_API void PL_put_variable(term_t);
+extern X_API int PL_put_pointer(term_t, void *);
+extern X_API int PL_put_string_chars(term_t, const char *);
+extern X_API int PL_put_term(term_t, term_t);
+extern X_API int PL_put_variable(term_t);
 extern X_API  int PL_compare(term_t, term_t);
 /* end PL_put_* functions =============================*/
 /* begin PL_unify_* functions =============================*/
diff --git a/library/yap2swi/yap2swi.c b/library/yap2swi/yap2swi.c
index a94b59578..6c035241c 100644
--- a/library/yap2swi/yap2swi.c
+++ b/library/yap2swi/yap2swi.c
@@ -788,7 +788,7 @@ X_API int PL_functor_arity(functor_t f)
 
 /* begin PL_put_* functions =============================*/
 
-X_API void PL_cons_functor(term_t d, functor_t f,...)
+X_API int PL_cons_functor(term_t d, functor_t f,...)
 {
   va_list ap;
   int arity, i;
@@ -797,12 +797,12 @@ X_API void PL_cons_functor(term_t d, functor_t f,...)
 
   if (IsAtomTerm((Term)ff)) {
     Yap_PutInSlot(d, (YAP_Term)f);
-    return;
+    return TRUE;
   }
   arity = ArityOfFunctor(ff);
   if (arity > TMP_BUF_SIZE/sizeof(YAP_CELL)) {
     fprintf(stderr,"PL_cons_functor: arity too large (%d)\n", arity); 
-    return;
+    return FALSE;
   }
   va_start (ap, f);
   for (i = 0; i < arity; i++) {
@@ -813,45 +813,51 @@ X_API void PL_cons_functor(term_t d, functor_t f,...)
     Yap_PutInSlot(d,YAP_MkPairTerm(tmp[0],tmp[1]));
   else
     Yap_PutInSlot(d,YAP_MkApplTerm((YAP_Functor)ff,arity,tmp));
+  return TRUE;
 }
 
-X_API void PL_cons_functor_v(term_t d, functor_t f,term_t a0)
+X_API int PL_cons_functor_v(term_t d, functor_t f,term_t a0)
 {
   int arity;
   Functor ff = SWIFunctorToFunctor(f);
 
   if (IsAtomTerm((Term)ff)) {
     Yap_PutInSlot(d,(Term)ff);
-    return;
+    return TRUE;
   }
   arity = ArityOfFunctor(ff);
   if (arity == 2 && ff == FunctorDot)
     Yap_PutInSlot(d,YAP_MkPairTerm(Yap_GetFromSlot(a0),Yap_GetFromSlot(a0+1)));    
   else
     Yap_PutInSlot(d,YAP_MkApplTerm((YAP_Functor)ff,arity,YAP_AddressFromSlot(a0)));
+  return TRUE;
 }
 
-X_API void PL_cons_list(term_t d, term_t h, term_t t)
+X_API int PL_cons_list(term_t d, term_t h, term_t t)
 {
   Yap_PutInSlot(d,YAP_MkPairTerm(Yap_GetFromSlot(h),Yap_GetFromSlot(t)));
+  return TRUE;
 }
 
-X_API void PL_put_atom(term_t t, atom_t a)
+X_API int PL_put_atom(term_t t, atom_t a)
 {
   Yap_PutInSlot(t,MkAtomTerm(SWIAtomToAtom(a)));
+  return TRUE;
 }
 
-X_API void PL_put_atom_chars(term_t t, const char *s)
+X_API int PL_put_atom_chars(term_t t, const char *s)
 {
   Yap_PutInSlot(t,MkAtomTerm(Yap_LookupAtom((char *)s)));
+  return TRUE;
 }
 
-X_API void PL_put_float(term_t t, double fl)
+X_API int PL_put_float(term_t t, double fl)
 {
   Yap_PutInSlot(t,YAP_MkFloatTerm(fl));
+  return TRUE;
 }
 
-X_API void PL_put_functor(term_t t, functor_t f)
+X_API int PL_put_functor(term_t t, functor_t f)
 {
   long int  arity;
   Functor ff = SWIFunctorToFunctor(f);
@@ -865,14 +871,16 @@ X_API void PL_put_functor(term_t t, functor_t f)
     else
       Yap_PutInSlot(t,YAP_MkNewApplTerm((YAP_Functor)ff,arity));
   }
+  return TRUE;
 }
 
-X_API void PL_put_integer(term_t t, long n)
+X_API int PL_put_integer(term_t t, long n)
 {
   Yap_PutInSlot(t,YAP_MkIntTerm(n));
+  return TRUE;
 }
 
-X_API void PL_put_int64(term_t t, int64_t n)
+X_API int PL_put_int64(term_t t, int64_t n)
 {
 #if USE_GMP
   char s[64];
@@ -881,17 +889,22 @@ X_API void PL_put_int64(term_t t, int64_t n)
   sprintf(s, "%lld", (long long int)n);
   mpz_init_set_str (&rop, s, 10);
   Yap_PutInSlot(t,YAP_MkBigNumTerm((void *)&rop));
+  return TRUE;
+#else
+  return FALSE;
 #endif
 }
 
-X_API void PL_put_list(term_t t)
+X_API int PL_put_list(term_t t)
 {
   Yap_PutInSlot(t,YAP_MkNewPairTerm());
+  return TRUE;
 }
 
-X_API void PL_put_list_chars(term_t t, const char *s)
+X_API int PL_put_list_chars(term_t t, const char *s)
 {
   Yap_PutInSlot(t,YAP_BufferToString((char *)s));
+  return TRUE;
 }
 
 X_API void PL_put_nil(term_t t)
@@ -902,25 +915,29 @@ X_API void PL_put_nil(term_t t)
 /* SWI: void PL_put_pointer(term_t -t, void *ptr)
    YAP: NO EQUIVALENT */
 /* SAM TO DO */
-X_API void PL_put_pointer(term_t t, void *ptr)
+X_API int PL_put_pointer(term_t t, void *ptr)
 {
   YAP_Term tptr = YAP_MkIntTerm((long int)ptr);
   Yap_PutInSlot(t,tptr);
+  return TRUE;
 }
 
-X_API void PL_put_string_chars(term_t t, const char *s)
+X_API int PL_put_string_chars(term_t t, const char *s)
 {
   Yap_PutInSlot(t,YAP_BufferToString((char *)s));
+  return TRUE;
 }
 
-X_API void PL_put_term(term_t d, term_t s)
+X_API int PL_put_term(term_t d, term_t s)
 {
   Yap_PutInSlot(d,Yap_GetFromSlot(s));
+  return TRUE;
 }
 
-X_API void PL_put_variable(term_t t)
+X_API int PL_put_variable(term_t t)
 {
   Yap_PutInSlot(t,YAP_MkVarTerm());
+  return TRUE;
 }
 
 /* end PL_put_* functions =============================*/