diff --git a/include/clasp/core/lispStream.h b/include/clasp/core/lispStream.h
index cf7f9f6152..80cca029d0 100644
--- a/include/clasp/core/lispStream.h
+++ b/include/clasp/core/lispStream.h
@@ -674,6 +674,7 @@ class StringInputStream_O : public StringStream_O {
   void unread_char(claspCharacter c);
   claspCharacter peek_char();
   int listen();
+  void clear_input();
 
   bool input_p() const;
   T_sp element_type() const;
@@ -739,7 +740,7 @@ class SynonymStream_O : public AnsiStream_O {
   T_sp length();
   T_sp position();
   T_sp set_position(T_sp pos);
-  int column();
+  int column() const;
   int set_column(int column);
 
   int input_handle();
@@ -794,7 +795,7 @@ class TwoWayStream_O : public AnsiStream_O {
   T_sp element_type() const;
 
   T_sp position();
-  int column();
+  int column() const;
   int set_column(int column);
 
   int input_handle();
@@ -841,7 +842,7 @@ class BroadcastStream_O : public AnsiStream_O {
   T_sp position();
   T_sp set_position(T_sp pos);
   T_sp string_length(T_sp string);
-  int column();
+  int column() const;
   int set_column(int column);
   T_sp close(T_sp abort);
 }; // BroadcastStream class
@@ -872,6 +873,7 @@ class ConcatenatedStream_O : public AnsiStream_O {
   claspCharacter read_char();
   void unread_char(claspCharacter c);
   int listen();
+  void clear_input();
 
   bool input_p() const;
   T_sp element_type() const;
@@ -923,7 +925,7 @@ class EchoStream_O : public AnsiStream_O {
   T_sp element_type() const;
 
   T_sp position();
-  int column();
+  int column() const;
   int set_column(int column);
 
   int input_handle();
diff --git a/src/core/lispStream.cc b/src/core/lispStream.cc
index 186c75c3f7..24bb1d336c 100644
--- a/src/core/lispStream.cc
+++ b/src/core/lispStream.cc
@@ -1267,6 +1267,8 @@ claspCharacter StringInputStream_O::peek_char() {
 
 int StringInputStream_O::listen() { return (_InputPosition < _InputLimit) ? CLASP_LISTEN_AVAILABLE : CLASP_LISTEN_EOF; }
 
+void StringInputStream_O::clear_input() {}
+
 T_sp StringInputStream_O::element_type() const { return _Contents->element_type(); }
 
 T_sp StringInputStream_O::position() { return Integer_O::create((gc::Fixnum)_InputPosition); }
@@ -1385,7 +1387,7 @@ T_sp TwoWayStream_O::element_type() const { return stream_element_type(_In); }
 
 T_sp TwoWayStream_O::position() { return nil<T_O>(); }
 
-int TwoWayStream_O::column() { return stream_column(_Out); }
+int TwoWayStream_O::column() const { return stream_column(_Out); }
 
 int TwoWayStream_O::set_column(int column) { return stream_set_column(_Out, column); }
 
@@ -1513,7 +1515,7 @@ T_sp BroadcastStream_O::string_length(T_sp string) {
                          : stream_string_length(oCar(cl__last(_Streams, clasp_make_fixnum(1))), string);
 }
 
-int BroadcastStream_O::column() { return _Streams.nilp() ? -1 : stream_column(oCar(_Streams)); }
+int BroadcastStream_O::column() const { return _Streams.nilp() ? -1 : stream_column(oCar(_Streams)); }
 
 int BroadcastStream_O::set_column(int column) {
   for (T_sp cur = _Streams; cur.consp(); cur = gc::As_unsafe<Cons_sp>(cur)->cdr()) {
@@ -1638,7 +1640,7 @@ T_sp EchoStream_O::element_type() const { return stream_element_type(_In); }
 
 T_sp EchoStream_O::position() { return nil<T_O>(); }
 
-int EchoStream_O::column() { return stream_column(_Out); }
+int EchoStream_O::column() const { return stream_column(_Out); }
 
 int EchoStream_O::set_column(int column) { return stream_set_column(_Out, column); }
 
@@ -1700,6 +1702,8 @@ CL_DEFUN T_sp cl__echo_stream_output_stream(T_sp strm) {
  */
 
 cl_index ConcatenatedStream_O::read_byte8(unsigned char* c, cl_index n) {
+  check_open();
+
   cl_index out = 0;
   while (out < n && !_List.nilp()) {
     cl_index delta = stream_read_byte8(oCar(_List), c + out, n - out);
@@ -1712,6 +1716,8 @@ cl_index ConcatenatedStream_O::read_byte8(unsigned char* c, cl_index n) {
 }
 
 T_sp ConcatenatedStream_O::read_byte() {
+  check_open();
+
   T_sp l = _List;
   T_sp c = nil<T_O>();
   while (!l.nilp()) {
@@ -1731,6 +1737,8 @@ bool ConcatenatedStream_O::input_p() const { return true; }
 T_sp ConcatenatedStream_O::element_type() const { return _List.nilp() ? _lisp->_true() : stream_element_type(oCar(_List)); }
 
 claspCharacter ConcatenatedStream_O::read_char() {
+  check_open();
+
   T_sp l = _List;
   claspCharacter c = EOF;
   while (!l.nilp()) {
@@ -1743,11 +1751,15 @@ claspCharacter ConcatenatedStream_O::read_char() {
 }
 
 void ConcatenatedStream_O::unread_char(claspCharacter c) {
+  check_open();
+
   unlikely_if(_List.nilp()) unread_error(asSmartPtr());
   stream_unread_char(oCar(_List), c);
 }
 
 int ConcatenatedStream_O::listen() {
+  check_open();
+
   while (!_List.nilp()) {
     int f = stream_listen(oCar(_List));
     if (f != CLASP_LISTEN_EOF) {
@@ -1758,6 +1770,13 @@ int ConcatenatedStream_O::listen() {
   return CLASP_LISTEN_EOF;
 }
 
+void ConcatenatedStream_O::clear_input() {
+  check_open();
+
+  if (_List.notnilp())
+    stream_clear_input(oCar(_List));
+}
+
 T_sp ConcatenatedStream_O::position() { return nil<T_O>(); }
 
 T_sp ConcatenatedStream_O::close(T_sp abort) {
@@ -1868,7 +1887,7 @@ T_sp SynonymStream_O::position() { return stream_position(stream()); }
 
 T_sp SynonymStream_O::set_position(T_sp pos) { return stream_set_position(stream(), pos); }
 
-int SynonymStream_O::column() { return stream_column(stream()); }
+int SynonymStream_O::column() const { return stream_column(stream()); }
 
 int SynonymStream_O::set_column(int column) { return stream_set_column(stream(), column); }