Index: less-656/filename.c
===================================================================
--- less-656.orig/filename.c
+++ less-656/filename.c
@@ -553,7 +553,7 @@ static FILE * shellcmd(constant char *cm
 #if HAVE_SHELL
 	constant char *shell;
 
-	shell = lgetenv("SHELL");
+	shell = lgetenv("LESSSHELL");
 	if (!isnullenv(shell))
 	{
 		char *scmd;
Index: less-656/less.hlp
===================================================================
--- less-656.orig/less.hlp
+++ less-656/less.hlp
@@ -109,7 +109,7 @@
   ___<_n_a_m_e_>             Display the setting of an option, by name.
   +_c_m_d                 Execute the less cmd each time a new file is examined.
 
-  !_c_o_m_m_a_n_d             Execute the shell command with $SHELL.
+  !_c_o_m_m_a_n_d             Execute the shell command with $LESSSHELL.
   #_c_o_m_m_a_n_d             Execute the shell command, expanded like a prompt.
   |XX_c_o_m_m_a_n_d            Pipe file between current pos & mark XX to shell command.
   s _f_i_l_e               Save input to a file.
Index: less-656/less.nro
===================================================================
--- less-656.orig/less.nro
+++ less-656/less.nro
@@ -468,7 +468,7 @@ A pound sign (#) is replaced by the name
 "!" with no shell command simply invokes a shell.
 If a \(haP (CONTROL-P) is entered immediately after the !,
 no "done" message is printed after the shell command is executed.
-On Unix systems, the shell is taken from the environment variable SHELL,
+On Unix systems, the shell is taken from the environment variable LESSSHELL,
 or defaults to "sh".
 On MS-DOS, Windows, and OS/2 systems, the shell is the normal command processor.
 .IP "# shell-command"
@@ -2493,7 +2493,7 @@ automatically when running in
 .IP PATH
 User's search path (used to find a lesskey file
 on MS-DOS, Windows, and OS/2 systems).
-.IP SHELL
+.IP LESSSHELL
 The shell used to execute the !\& command, as well as to expand filenames.
 .IP TERM
 The type of terminal on which
Index: less-656/lsystem.c
===================================================================
--- less-656.orig/lsystem.c
+++ less-656/lsystem.c
@@ -120,13 +120,13 @@ public void lsystem(constant char *cmd,
 
 	/*
 	 * Pass the command to the system to be executed.
-	 * If we have a SHELL environment variable, use
+	 * If we have a LESSSHELL environment variable, use
 	 * <$SHELL -c "command"> instead of just <command>.
 	 * If the command is empty, just invoke a shell.
 	 */
 #if HAVE_SHELL
 	p = NULL;
-	if ((shell = lgetenv("SHELL")) != NULL && *shell != '\0')
+	if ((shell = lgetenv("LESSSHELL")) != NULL && *shell != '\0')
 	{
 		if (*cmd == '\0')
 			p = save(shell);