diff --git a/src/c/file.d b/src/c/file.d
index 3adaf6953..cbedb4b7c 100755
--- a/src/c/file.d
+++ b/src/c/file.d
@@ -4993,14 +4993,20 @@ cl_streamp(cl_object strm)
  */
 
 cl_object
-si_copy_stream(cl_object in, cl_object out)
+si_copy_stream(cl_object in, cl_object out, cl_object wait)
 {
   ecl_character c;
+  if ((wait == ECL_NIL) && !ecl_listen_stream(in)) {
+    return ECL_NIL;
+  }
   for (c = ecl_read_char(in); c != EOF; c = ecl_read_char(in)) {
     ecl_write_char(c, out);
+    if ((wait == ECL_NIL) && !ecl_listen_stream(in)) {
+      break;
+    }
   }
   ecl_force_output(out);
-  @(return ECL_T);
+  @(return c==EOF);
 }
 
 
diff --git a/src/c/symbols_list.h b/src/c/symbols_list.h
index 7630bd891..0c400815e 100755
--- a/src/c/symbols_list.h
+++ b/src/c/symbols_list.h
@@ -1141,7 +1141,7 @@ cl_symbols[] = {
 {SYS_ "COPY-TO-SIMPLE-BASE-STRING", SI_ORDINARY, si_copy_to_simple_base_string, 1, OBJNULL},
 {SYS_ "COMPILED-FUNCTION-BLOCK", SI_ORDINARY, si_compiled_function_block, 1, OBJNULL},
 {EXT_ "COMPILED-FUNCTION-NAME", EXT_ORDINARY, si_compiled_function_name, 1, OBJNULL},
-{SYS_ "COPY-STREAM", SI_ORDINARY, si_copy_stream, 1, OBJNULL},
+{SYS_ "COPY-STREAM", SI_ORDINARY, si_copy_stream, 3, OBJNULL},
 {SYS_ "DESTRUCTURE", SI_ORDINARY, NULL, -1, OBJNULL},
 {SYS_ "DO-READ-SEQUENCE", SI_ORDINARY, si_do_read_sequence, 4, OBJNULL},
 {SYS_ "DO-WRITE-SEQUENCE", SI_ORDINARY, si_do_write_sequence, 4, OBJNULL},
diff --git a/src/cmp/proclamations.lsp b/src/cmp/proclamations.lsp
index 05884ce53..2c58ed650 100644
--- a/src/cmp/proclamations.lsp
+++ b/src/cmp/proclamations.lsp
@@ -1152,7 +1152,7 @@
 (proclamation si:open-unix-socket-stream (string) stream)
 #+wants-sockets
 (proclamation si:lookup-host-entry (t) (values (or null string) list list))
-(proclamation si:copy-stream (stream stream) t)
+(proclamation si:copy-stream (stream stream wait) t)
 (proclamation si:make-encoding (t) hash-table)
 (proclamation si:load-encoding (t) t)
 
diff --git a/src/h/external.h b/src/h/external.h
index dba2dbda3..1d7b6870e 100755
--- a/src/h/external.h
+++ b/src/h/external.h
@@ -690,7 +690,7 @@ extern ECL_API cl_object cl_stream_external_format(cl_object strm);
 extern ECL_API cl_object cl_file_length(cl_object strm);
 extern ECL_API cl_object si_get_string_input_stream_index(cl_object strm);
 extern ECL_API cl_object si_make_string_output_stream_from_string(cl_object strng);
-extern ECL_API cl_object si_copy_stream(cl_object in, cl_object out);
+extern ECL_API cl_object si_copy_stream(cl_object in, cl_object out, cl_object wait);
 extern ECL_API cl_object cl_open_stream_p(cl_object strm);
 extern ECL_API cl_object cl_make_broadcast_stream _ECL_ARGS((cl_narg narg, ...));
 extern ECL_API cl_object cl_broadcast_stream_streams(cl_object strm);