diff --git a/changes4.3.html b/changes4.3.html
index 0a589bd4c..c27200c89 100644
--- a/changes4.3.html
+++ b/changes4.3.html
@@ -16,6 +16,7 @@
 
 <h2>Yap-4.3.23:</h2>
 <ul>
+	<li>UPDATE: fixed shell/1 and shell/2 in library(system). (Nicos)</li>
 	<li>UPDATE: new Logtalk version (2.13.0).</li>
 	<li>FIXED: <code>\newline</code> in strings (Roberto Bagnara). </li>
 	<li>FIXED: avoid reincluding of <code>c_interface.h</code> (Roberto
diff --git a/library/system.yap b/library/system.yap
index 6e43d9297..db542f2ec 100644
--- a/library/system.yap
+++ b/library/system.yap
@@ -348,8 +348,9 @@ shell(Command) :-
 	G = shell(Command),
 	check_command(Command, G),
 	get_shell(Shell),
-	atom_codes(Command, SC),
-	append(Shell, SC, ShellCommand),
+	atom_codes(Command, SC0),
+	protect_command(SC0, SC),
+	append(Shell, [0'"|SC], ShellCommand),
 	atom_codes(FullCommand, ShellCommand),
 	exec_command(FullCommand, 0, 1, 2, PID, Error),
 	handle_system_error(Error, off, G),
@@ -360,14 +361,20 @@ shell(Command, Status) :-
 	G = shell(Command, Status),
 	check_command(Command, G),
 	get_shell(Shell),
-	atom_codes(Command, SC),
-	append(Shell, SC, ShellCommand),
+	atom_codes(Command, SC0),
+	protect_command(SC0, SC),
+	append(Shell, [0'"|SC], ShellCommand),
 	atom_codes(FullCommand, ShellCommand),
 	exec_command(FullCommand, 0, 1, 2, PID, Error),
 	handle_system_error(Error, off, G),
 	wait(PID, Status,Error),
 	handle_system_error(Error, off, G).
 
+
+protect_command([], [0'"]).
+protect_command([H|L], [H|NL]) :-
+	protect_command(L, NL).
+
 get_shell0(Shell) :-
 	getenv('SHELL', Shell), !.
 get_shell0(Shell) :-