diff --git a/C/pl-yap.c b/C/pl-yap.c
index f95760531..2351bfc11 100644
--- a/C/pl-yap.c
+++ b/C/pl-yap.c
@@ -623,7 +623,8 @@ currentOperator(Module m, atom_t name, int kind, int *type, int *priority)
 
 int
 numberVars(term_t t, nv_options *opts, int n ARG_LD) {
-  return Yap_NumberVars(YAP_GetFromSlot(t), n, TRUE);
+
+  return Yap_NumberVars(YAP_GetFromSlot(t), n, opts->singletons);
 }
 
 		 /*******************************
diff --git a/C/utilpreds.c b/C/utilpreds.c
index ab2face96..a0bf851b5 100644
--- a/C/utilpreds.c
+++ b/C/utilpreds.c
@@ -4254,7 +4254,7 @@ numbervar(Int id)
 {
   Term ts[1];
   ts[0] = MkIntegerTerm(id);
-  return Yap_MkApplTerm(FunctorVar, 1, ts);
+  return Yap_MkApplTerm(LOCAL_FunctorVar, 1, ts);
 }
 
 static Term
@@ -4262,7 +4262,7 @@ numbervar_singleton(void)
 {
   Term ts[1];
   ts[0] = MkIntegerTerm(-1);
-  return Yap_MkApplTerm(FunctorVar, 1, ts);
+  return Yap_MkApplTerm(LOCAL_FunctorVar, 1, ts);
 }
 
 static void
diff --git a/C/write.c b/C/write.c
index 5bcdf8122..37f9c8ccd 100644
--- a/C/write.c
+++ b/C/write.c
@@ -1013,7 +1013,7 @@ writeTerm(Term t, int p, int depth, int rinfixarg, struct write_globs *wglb, str
 	wrputc(')', wglb->stream);
 	lastw = separator;
       }
-    } else if (wglb->Handle_vars && functor == FunctorVar) {
+    } else if (wglb->Handle_vars && functor == LOCAL_FunctorVar) {
       Term ti = ArgOfTerm(1, t);
       if (lastw == alphanum) {
 	wrputc(' ', wglb->stream);
diff --git a/H/dlocals.h b/H/dlocals.h
index 2ddd91f16..fe264da61 100644
--- a/H/dlocals.h
+++ b/H/dlocals.h
@@ -427,4 +427,6 @@
 #define LOCAL_FPreds LOCAL->FPreds_
 #define REMOTE_FPreds(wid) REMOTE(wid)->FPreds_
 #endif /* LOW_PROF */
+#define LOCAL_FunctorVar LOCAL->FunctorVar_
+#define REMOTE_FunctorVar(wid) REMOTE(wid)->FunctorVar_
 
diff --git a/H/hlocals.h b/H/hlocals.h
index c71a0355b..c55a5e4f9 100644
--- a/H/hlocals.h
+++ b/H/hlocals.h
@@ -240,4 +240,5 @@ typedef struct worker_local {
   FILE*  FProf_;
   FILE*  FPreds_;
 #endif /* LOW_PROF */
+  Functor  FunctorVar_;
 } w_local;
diff --git a/H/iatoms.h b/H/iatoms.h
index af72f9f4d..de3159edd 100644
--- a/H/iatoms.h
+++ b/H/iatoms.h
@@ -311,6 +311,7 @@
   AtomUserOut = Yap_LookupAtom("user_output");
   AtomVBar = Yap_LookupAtom("|");
   AtomVar = Yap_FullLookupAtom("$VAR");
+  AtomHiddenVar = Yap_FullLookupAtom("$V");
   AtomVariable = Yap_LookupAtom("variable");
   AtomVersionNumber = Yap_FullLookupAtom("$version_name");
   AtomWakeUpGoal = Yap_FullLookupAtom("$wake_up_goal");
@@ -428,3 +429,4 @@
   FunctorUPlus = Yap_MkFunctor(AtomPlus,1);
   FunctorVBar = Yap_MkFunctor(AtomVBar,2);
   FunctorVar = Yap_MkFunctor(AtomVar,1);
+  FunctorHiddenVar = Yap_MkFunctor(AtomHiddenVar,1);
diff --git a/H/ilocals.h b/H/ilocals.h
index 6c3ea292e..5fd0d935a 100644
--- a/H/ilocals.h
+++ b/H/ilocals.h
@@ -240,4 +240,5 @@ static void InitWorker(int wid) {
   REMOTE_FProf(wid) = NULL;
   REMOTE_FPreds(wid) = NULL;
 #endif /* LOW_PROF */
+  REMOTE_FunctorVar(wid) = FunctorVar;
 }
diff --git a/H/ratoms.h b/H/ratoms.h
index 7f7124d5b..913ef73a3 100644
--- a/H/ratoms.h
+++ b/H/ratoms.h
@@ -311,6 +311,7 @@
   AtomUserOut = AtomAdjust(AtomUserOut);
   AtomVBar = AtomAdjust(AtomVBar);
   AtomVar = AtomAdjust(AtomVar);
+  AtomHiddenVar = AtomAdjust(AtomHiddenVar);
   AtomVariable = AtomAdjust(AtomVariable);
   AtomVersionNumber = AtomAdjust(AtomVersionNumber);
   AtomWakeUpGoal = AtomAdjust(AtomWakeUpGoal);
@@ -428,3 +429,4 @@
   FunctorUPlus = FuncAdjust(FunctorUPlus);
   FunctorVBar = FuncAdjust(FunctorVBar);
   FunctorVar = FuncAdjust(FunctorVar);
+  FunctorHiddenVar = FuncAdjust(FunctorHiddenVar);
diff --git a/H/rlocals.h b/H/rlocals.h
index a27432bda..90a66d373 100644
--- a/H/rlocals.h
+++ b/H/rlocals.h
@@ -240,4 +240,5 @@ static void RestoreWorker(int wid USES_REGS) {
 
 
 #endif /* LOW_PROF */
+
 }
diff --git a/H/tatoms.h b/H/tatoms.h
index ce5498ff0..16318620e 100644
--- a/H/tatoms.h
+++ b/H/tatoms.h
@@ -620,6 +620,8 @@
 #define AtomVBar Yap_heap_regs->AtomVBar_
   Atom AtomVar_;
 #define AtomVar Yap_heap_regs->AtomVar_
+  Atom AtomHiddenVar_;
+#define AtomHiddenVar Yap_heap_regs->AtomHiddenVar_
   Atom AtomVariable_;
 #define AtomVariable Yap_heap_regs->AtomVariable_
   Atom AtomVersionNumber_;
@@ -854,3 +856,5 @@
 #define FunctorVBar Yap_heap_regs->FunctorVBar_
   Functor FunctorVar_;
 #define FunctorVar Yap_heap_regs->FunctorVar_
+  Functor FunctorHiddenVar_;
+#define FunctorHiddenVar Yap_heap_regs->FunctorHiddenVar_
diff --git a/misc/ATOMS b/misc/ATOMS
index aa8c4edf6..339022b8a 100644
--- a/misc/ATOMS
+++ b/misc/ATOMS
@@ -316,6 +316,7 @@ A	UserIn			N	"user_input"
 A	UserOut			N	"user_output"
 A	VBar			N	"|"
 A	Var			F	"$VAR"
+A	HiddenVar		F	"$V"
 A	Variable		N	"variable"
 A	VersionNumber		F	"$version_name"
 A	WakeUpGoal		F	"$wake_up_goal"
@@ -433,4 +434,5 @@ F	UMinus			Minus		1
 F	UPlus			Plus		1
 F	VBar			VBar		2
 F	Var			Var		1
+F	HiddenVar		HiddenVar	1
 
diff --git a/misc/LOCALS b/misc/LOCALS
index 534da8de5..dacd39c32 100644
--- a/misc/LOCALS
+++ b/misc/LOCALS
@@ -269,4 +269,6 @@ FILE*				FProf					=NULL
 FILE*				FPreds					=NULL
 #endif /* LOW_PROF */
 
+Functor				FunctorVar				=FunctorVar
+
 END_WORKER_LOCAL
diff --git a/os/pl-write.c b/os/pl-write.c
index 6b7c5813e..ad6e31d6d 100644
--- a/os/pl-write.c
+++ b/os/pl-write.c
@@ -490,9 +490,15 @@ pl_write_canonical2(term_t stream, term_t term)
   options.functor = FUNCTOR_isovar1;
   options.on_attvar = AV_SKIP;
   options.singletons = TRUE;
+#if __YAP_PROLOG__
+  LOCAL_FunctorVar = FunctorHiddenVar;
+#endif
   numberVars(term, &options, 0 PASS_LD);
   rc = do_write2(stream, term,
 		 PL_WRT_QUOTED|PL_WRT_IGNOREOPS|PL_WRT_NUMBERVARS);
+#if __YAP_PROLOG__
+  LOCAL_FunctorVar = FunctorVar;
+#endif
   PL_discard_foreign_frame(fid);
 
   return rc;