diff --git a/C/bignum.c b/C/bignum.c
index adcb5031f..66bf3672c 100644
--- a/C/bignum.c
+++ b/C/bignum.c
@@ -100,12 +100,23 @@ p_is_bignum(void)
   Term t = Deref(ARG1);
   return(IsNonVarTerm(t) && IsApplTerm(t) && FunctorOfTerm(t) == FunctorBigInt);
 #else
-  return(FALSE);
+  return FALSE;
+#endif
+}
+
+static Int 
+p_has_bignums(void)
+{
+#ifdef USE_GMP
+  return TRUE;
+#else
+  return FALSE;
 #endif
 }
 
 void
 Yap_InitBigNums(void)
 {
+  Yap_InitCPred("$has_bignums", 0, p_has_bignums, SafePredFlag|HiddenPredFlag);
   Yap_InitCPred("$bignum", 1, p_is_bignum, SafePredFlag|HiddenPredFlag);
 }
diff --git a/C/iopreds.c b/C/iopreds.c
index 2a15c70fc..35487d529 100644
--- a/C/iopreds.c
+++ b/C/iopreds.c
@@ -1080,6 +1080,16 @@ ReadlineGetc(int sno)
 
 #endif /* HAVE_LIBREADLINE */
 
+static Int
+p_has_readline(void)
+{
+#if HAVE_LIBREADLINE
+  return TRUE;
+#else
+  return FALSE;
+#endif
+}
+
 
 int
 Yap_GetCharForSIGINT(void)
@@ -5937,6 +5947,7 @@ Yap_InitIOPreds(void)
 #endif
   Yap_InitCPred ("$same_file", 2, p_same_file, SafePredFlag|SyncPredFlag|HiddenPredFlag);
   Yap_InitCPred ("$float_format", 1, p_float_format, SafePredFlag|SyncPredFlag|HiddenPredFlag);
+  Yap_InitCPred ("$has_readline", 0, p_has_readline, SafePredFlag|HiddenPredFlag);
 
   Yap_InitReadUtil ();
 #if USE_SOCKET
diff --git a/changes-5.1.html b/changes-5.1.html
index 31cd83802..61fdb2ec2 100644
--- a/changes-5.1.html
+++ b/changes-5.1.html
@@ -16,6 +16,8 @@
 
 <h2>Yap-5.1.3:</h2>
 <ul>
+<li> FIXED: support checking for big_nums and readline. (obs from
+Rui Camacho)</li>
 <li> FIXED: make thread_create more compatible with SWI. (obs from
 Paulo Moura)</li>
 <li> FIXED: give startup path to chr. (obs from Paulo Moura)</li>
diff --git a/docs/yap.tex b/docs/yap.tex
index c3da20750..ff4861f72 100644
--- a/docs/yap.tex
+++ b/docs/yap.tex
@@ -6753,9 +6753,9 @@ Just fail
 @item system_options
 @findex system_options (yap_flag/2 option)
 @* This read only flag tells which options were used to compile
-YAP. Currently it informs whether the system supports
+YAP. Currently it informs whether the system supports @code{big_numbers},
 @code{coroutining}, @code{depth_limit}, @code{low_level_tracer},
-@code{or-parallelism}, @code{rational_trees}, @code{tabling},
+@code{or-parallelism}, @code{rational_trees}, @code{readline}, @code{tabling},
 @code{threads}, or the @code{wam_profiler}.
 
 @item tabling_mode
diff --git a/pl/directives.yap b/pl/directives.yap
index b99895e86..69aef54c5 100644
--- a/pl/directives.yap
+++ b/pl/directives.yap
@@ -492,6 +492,8 @@ yap_flag(single_var_warnings,X) :-
 yap_flag(system_options,X) :-
 	'$system_options'(X).
 
+'$system_options'(big_numbers) :-
+	'$has_bignums'.
 '$system_options'(coroutining) :-
 	'$yap_has_coroutining'.
 '$system_options'(depth_limit) :-
@@ -502,6 +504,8 @@ yap_flag(system_options,X) :-
 	\+ '$undefined'('$yapor_on', prolog).
 '$system_options'(rational_trees) :-
 	'$yap_has_rational_trees'.
+'$system_options'(readline) :-
+	'$has_readline'.
 '$system_options'(tabling) :-
 	\+ '$undefined'('$do_table'(_,_), prolog).
 '$system_options'(threads) :-