diff --git a/cmd-attach-session.c b/cmd-attach-session.c
index f889019c..b2a2f8c5 100644
--- a/cmd-attach-session.c
+++ b/cmd-attach-session.c
@@ -34,18 +34,18 @@ enum cmd_retval	cmd_attach_session_exec(struct cmd *, struct cmd_q *);
 
 const struct cmd_entry cmd_attach_session_entry = {
 	"attach-session", "attach",
-	"c:drt:", 0, 0,
-	"[-dr] [-c working-directory] " CMD_TARGET_SESSION_USAGE,
+	"c:dErt:", 0, 0,
+	"[-dEr] [-c working-directory] " CMD_TARGET_SESSION_USAGE,
 	CMD_STARTSERVER,
 	cmd_attach_session_exec
 };
 
 enum cmd_retval
 cmd_attach_session(struct cmd_q *cmdq, const char *tflag, int dflag, int rflag,
-    const char *cflag)
+    const char *cflag, int Eflag)
 {
 	struct session		*s;
-	struct client		*c;
+	struct client		*c = cmdq->client, *c_loop;
 	struct winlink		*wl = NULL;
 	struct window		*w = NULL;
 	struct window_pane	*wp = NULL;
@@ -79,9 +79,9 @@ cmd_attach_session(struct cmd_q *cmdq, const char *tflag, int dflag, int rflag,
 			wl = winlink_find_by_window(&s->windows, w);
 	}
 
-	if (cmdq->client == NULL)
+	if (c == NULL)
 		return (CMD_RETURN_NORMAL);
-	if (server_client_check_nested(cmdq->client)) {
+	if (server_client_check_nested(c)) {
 		cmdq_error(cmdq, "sessions should be nested with care, "
 		    "unset $TMUX to force");
 		return (CMD_RETURN_ERROR);
@@ -93,18 +93,18 @@ cmd_attach_session(struct cmd_q *cmdq, const char *tflag, int dflag, int rflag,
 		session_set_current(s, wl);
 	}
 
-	if (cmdq->client->session != NULL) {
+	if (c->session != NULL) {
 		if (dflag) {
 			/*
 			 * Can't use server_write_session in case attaching to
 			 * the same session as currently attached to.
 			 */
-			TAILQ_FOREACH(c, &clients, entry) {
-				if (c->session != s || c == cmdq->client)
+			TAILQ_FOREACH(c_loop, &clients, entry) {
+				if (c_loop->session != s || c == c)
 					continue;
 				server_write_client(c, MSG_DETACH,
-				    c->session->name,
-				    strlen(c->session->name) + 1);
+				    c_loop->session->name,
+				    strlen(c_loop->session->name) + 1);
 			}
 		}
 
@@ -126,13 +126,13 @@ cmd_attach_session(struct cmd_q *cmdq, const char *tflag, int dflag, int rflag,
 			s->cwd = fd;
 		}
 
-		cmdq->client->session = s;
-		notify_attached_session_changed(cmdq->client);
+		c->session = s;
+		notify_attached_session_changed(c);
 		session_update_activity(s);
-		server_redraw_client(cmdq->client);
+		server_redraw_client(c);
 		s->curw->flags &= ~WINLINK_ALERTFLAGS;
 	} else {
-		if (server_client_open(cmdq->client, &cause) != 0) {
+		if (server_client_open(c, &cause) != 0) {
 			cmdq_error(cmdq, "open terminal failed: %s", cause);
 			free(cause);
 			return (CMD_RETURN_ERROR);
@@ -157,23 +157,26 @@ cmd_attach_session(struct cmd_q *cmdq, const char *tflag, int dflag, int rflag,
 		}
 
 		if (rflag)
-			cmdq->client->flags |= CLIENT_READONLY;
+			c->flags |= CLIENT_READONLY;
 
 		if (dflag) {
 			server_write_session(s, MSG_DETACH, s->name,
 			    strlen(s->name) + 1);
 		}
 
-		update = options_get_string(&s->options, "update-environment");
-		environ_update(update, &cmdq->client->environ, &s->environ);
+		if (!Eflag) {
+			update = options_get_string(&s->options,
+			    "update-environment");
+			environ_update(update, &c->environ, &s->environ);
+		}
 
-		cmdq->client->session = s;
-		notify_attached_session_changed(cmdq->client);
+		c->session = s;
+		notify_attached_session_changed(c);
 		session_update_activity(s);
-		server_redraw_client(cmdq->client);
+		server_redraw_client(c);
 		s->curw->flags &= ~WINLINK_ALERTFLAGS;
 
-		server_write_ready(cmdq->client);
+		server_write_ready(c);
 		cmdq->client_exit = 0;
 	}
 	recalculate_sizes();
@@ -188,5 +191,6 @@ cmd_attach_session_exec(struct cmd *self, struct cmd_q *cmdq)
 	struct args	*args = self->args;
 
 	return (cmd_attach_session(cmdq, args_get(args, 't'),
-	    args_has(args, 'd'), args_has(args, 'r'), args_get(args, 'c')));
+	    args_has(args, 'd'), args_has(args, 'r'), args_get(args, 'c'),
+	    args_has(args, 'E')));
 }
diff --git a/cmd-new-session.c b/cmd-new-session.c
index 0fb849e2..1533e5f0 100644
--- a/cmd-new-session.c
+++ b/cmd-new-session.c
@@ -37,8 +37,8 @@ enum cmd_retval	 cmd_new_session_exec(struct cmd *, struct cmd_q *);
 
 const struct cmd_entry cmd_new_session_entry = {
 	"new-session", "new",
-	"Ac:dDF:n:Ps:t:x:y:", 0, -1,
-	"[-AdDP] [-c start-directory] [-F format] [-n window-name] "
+	"Ac:dDEF:n:Ps:t:x:y:", 0, -1,
+	"[-AdDEP] [-c start-directory] [-F format] [-n window-name] "
 	"[-s session-name] " CMD_TARGET_SESSION_USAGE " [-x width] "
 	"[-y height] [command]",
 	CMD_STARTSERVER,
@@ -91,7 +91,8 @@ cmd_new_session_exec(struct cmd *self, struct cmd_q *cmdq)
 		if (session_find(newname) != NULL) {
 			if (args_has(args, 'A')) {
 				return (cmd_attach_session(cmdq, newname,
-				    args_has(args, 'D'), 0, NULL));
+				    args_has(args, 'D'), 0, NULL,
+				    args_has(args, 'E')));
 			}
 			cmdq_error(cmdq, "duplicate session: %s", newname);
 			return (CMD_RETURN_ERROR);
@@ -230,9 +231,11 @@ cmd_new_session_exec(struct cmd *self, struct cmd_q *cmdq)
 
 	/* Construct the environment. */
 	environ_init(&env);
-	update = options_get_string(&global_s_options, "update-environment");
-	if (c != NULL)
+	if (c != NULL && !args_has(args, 'E')) {
+		update = options_get_string(&global_s_options,
+		    "update-environment");
 		environ_update(update, &c->environ, &env);
+	}
 
 	/* Create the new session. */
 	idx = -1 - options_get_number(&global_s_options, "base-index");
diff --git a/cmd-switch-client.c b/cmd-switch-client.c
index 369fc917..23751d73 100644
--- a/cmd-switch-client.c
+++ b/cmd-switch-client.c
@@ -31,8 +31,8 @@ enum cmd_retval	 cmd_switch_client_exec(struct cmd *, struct cmd_q *);
 
 const struct cmd_entry cmd_switch_client_entry = {
 	"switch-client", "switchc",
-	"lc:npt:rT:", 0, 0,
-	"[-lnpr] [-c target-client] [-t target-session] [-T key-table]",
+	"lc:Enpt:rT:", 0, 0,
+	"[-Elnpr] [-c target-client] [-t target-session] [-T key-table]",
 	CMD_READONLY,
 	cmd_switch_client_exec
 };
@@ -119,7 +119,7 @@ cmd_switch_client_exec(struct cmd *self, struct cmd_q *cmdq)
 		}
 	}
 
-	if (c != NULL && s != c->session) {
+	if (c != NULL && s != c->session && !args_has(args, 'E')) {
 		update = options_get_string(&s->options, "update-environment");
 		environ_update(update, &c->environ, &s->environ);
 	}
diff --git a/tmux.1 b/tmux.1
index 7ad33530..16e979ad 100644
--- a/tmux.1
+++ b/tmux.1
@@ -670,7 +670,7 @@ section.
 The following commands are available to manage clients and sessions:
 .Bl -tag -width Ds
 .It Xo Ic attach-session
-.Op Fl dr
+.Op Fl dEr
 .Op Fl c Ar working-directory
 .Op Fl t Ar target-session
 .Xc
@@ -709,6 +709,12 @@ session.
 .Fl c
 will set the session working directory (used for new windows) to
 .Ar working-directory .
+.Pp
+If
+.Fl E
+is used,
+.Ic update-environment
+option will not be applied.
 .It Xo Ic detach-client
 .Op Fl P
 .Op Fl a
@@ -783,7 +789,7 @@ command.
 Lock all clients attached to
 .Ar target-session .
 .It Xo Ic new-session
-.Op Fl AdDP
+.Op Fl AdDEP
 .Op Fl c Ar start-directory
 .Op Fl F Ar format
 .Op Fl n Ar window-name
@@ -858,6 +864,13 @@ By default, it uses the format
 .Ql #{session_name}:
 but a different format may be specified with
 .Fl F .
+.Pp
+If
+.Fl E
+is used,
+.Ic update-environment
+option will not be applied.
+.Ic update-environment .
 .It Xo Ic refresh-client
 .Op Fl S
 .Op Fl t Ar target-client
@@ -912,7 +925,7 @@ Suspend a client by sending
 .Dv SIGTSTP
 (tty stop).
 .It Xo Ic switch-client
-.Op Fl lnpr
+.Op Fl Elnpr
 .Op Fl c Ar target-client
 .Op Fl t Ar target-session
 .Op Fl T Ar key-table
@@ -934,6 +947,12 @@ toggles whether a client is read-only (see the
 .Ic attach-session
 command).
 .Pp
+If
+.Fl E
+is used,
+.Ic update-environment
+option will not be applied.
+.Pp
 .Fl T
 sets the client's key table; the next key from the client will be interpreted from
 .Ar key-table .
diff --git a/tmux.h b/tmux.h
index 4ddf5c4a..265fdc40 100644
--- a/tmux.h
+++ b/tmux.h
@@ -1801,7 +1801,7 @@ extern const struct cmd_entry cmd_wait_for_entry;
 
 /* cmd-attach-session.c */
 enum cmd_retval	 cmd_attach_session(struct cmd_q *, const char *, int, int,
-		     const char *);
+		     const char *, int);
 
 /* cmd-list.c */
 struct cmd_list	*cmd_list_parse(int, char **, const char *, u_int, char **);