diff --git a/cmd-set-buffer.c b/cmd-set-buffer.c
index f67f7a0c..0942da9a 100644
--- a/cmd-set-buffer.c
+++ b/cmd-set-buffer.c
@@ -24,15 +24,15 @@
 #include "tmux.h"
 
 /*
- * Add or set a paste buffer.
+ * Add, set, or append to a paste buffer.
  */
 
 enum cmd_retval	 cmd_set_buffer_exec(struct cmd *, struct cmd_q *);
 
 const struct cmd_entry cmd_set_buffer_entry = {
 	"set-buffer", "setb",
-	"b:", 1, 1,
-	CMD_BUFFER_USAGE " data",
+	"ab:", 1, 1,
+	"[-a] " CMD_BUFFER_USAGE " data",
 	0,
 	NULL,
 	cmd_set_buffer_exec
@@ -41,35 +41,55 @@ const struct cmd_entry cmd_set_buffer_entry = {
 enum cmd_retval
 cmd_set_buffer_exec(struct cmd *self, struct cmd_q *cmdq)
 {
-	struct args	*args = self->args;
-	u_int		 limit;
-	char		*pdata, *cause;
-	size_t		 psize;
-	int		 buffer;
+	struct args		*args = self->args;
+	struct paste_buffer	*pb;
+	u_int			 limit;
+	char			*pdata, *cause;
+	size_t			 psize, newsize;
+	int			 buffer;
 
 	limit = options_get_number(&global_options, "buffer-limit");
 
-	pdata = xstrdup(args->argv[0]);
-	psize = strlen(pdata);
+	psize = 0;
+	pdata = NULL;
 
-	if (!args_has(args, 'b')) {
+	pb = NULL;
+	buffer = -1;
+
+	if (args_has(args, 'b')) {
+		buffer = args_strtonum(args, 'b', 0, INT_MAX, &cause);
+		if (cause != NULL) {
+			cmdq_error(cmdq, "buffer %s", cause);
+			free(cause);
+			return (CMD_RETURN_ERROR);
+		}
+		pb = paste_get_index(&global_buffers, buffer);
+		if (pb == NULL) {
+			cmdq_error(cmdq, "no buffer %d", buffer);
+			return (CMD_RETURN_ERROR);
+		}
+	} else if (args_has(args, 'a')) {
+		pb = paste_get_top(&global_buffers);
+		if (pb != NULL)
+			buffer = 0;
+	}
+
+	if (args_has(args, 'a') && pb != NULL) {
+		psize = pb->size;
+		pdata = xmalloc(psize);
+		memcpy(pdata, pb->data, psize);
+	}
+
+	newsize = strlen(args->argv[0]);
+
+	pdata = xrealloc(pdata, 1, psize + newsize);
+	memcpy(pdata + psize, args->argv[0], newsize);
+	psize += newsize;
+
+	if (buffer == -1)
 		paste_add(&global_buffers, pdata, psize, limit);
-		return (CMD_RETURN_NORMAL);
-	}
-
-	buffer = args_strtonum(args, 'b', 0, INT_MAX, &cause);
-	if (cause != NULL) {
-		cmdq_error(cmdq, "buffer %s", cause);
-		free(cause);
-		free(pdata);
-		return (CMD_RETURN_ERROR);
-	}
-
-	if (paste_replace(&global_buffers, buffer, pdata, psize) != 0) {
-		cmdq_error(cmdq, "no buffer %d", buffer);
-		free(pdata);
-		return (CMD_RETURN_ERROR);
-	}
+	else
+		paste_replace(&global_buffers, buffer, pdata, psize);
 
 	return (CMD_RETURN_NORMAL);
 }
diff --git a/mode-key.c b/mode-key.c
index 80a2464d..7f2b9471 100644
--- a/mode-key.c
+++ b/mode-key.c
@@ -100,6 +100,7 @@ const struct mode_key_cmdstr mode_key_cmdstr_choice[] = {
 
 /* Copy keys command strings. */
 const struct mode_key_cmdstr mode_key_cmdstr_copy[] = {
+	{ MODEKEYCOPY_APPENDSELECTION, "append-selection" },
 	{ MODEKEYCOPY_BACKTOINDENTATION, "back-to-indentation" },
 	{ MODEKEYCOPY_BOTTOMLINE, "bottom-line" },
 	{ MODEKEYCOPY_CANCEL, "cancel" },
@@ -272,6 +273,7 @@ const struct mode_key_entry mode_key_vi_copy[] = {
 	{ '9',			    0, MODEKEYCOPY_STARTNUMBERPREFIX },
 	{ ':',			    0, MODEKEYCOPY_GOTOLINE },
 	{ '?',			    0, MODEKEYCOPY_SEARCHUP },
+	{ 'A',			    0, MODEKEYCOPY_APPENDSELECTION },
 	{ 'B',			    0, MODEKEYCOPY_PREVIOUSSPACE },
 	{ 'D',			    0, MODEKEYCOPY_COPYENDOFLINE },
 	{ 'E',			    0, MODEKEYCOPY_NEXTSPACEEND },
diff --git a/paste.c b/paste.c
index 946935a3..4ec87f35 100644
--- a/paste.c
+++ b/paste.c
@@ -172,7 +172,7 @@ paste_print(struct paste_buffer *pb, size_t width)
 
 /* Paste into a window pane, filtering '\n' according to separator. */
 void
-paste_send_pane (struct paste_buffer *pb, struct window_pane *wp,
+paste_send_pane(struct paste_buffer *pb, struct window_pane *wp,
     const char *sep, int bracket)
 {
 	const char	*data = pb->data, *end = data + pb->size, *lf;
diff --git a/tmux.1 b/tmux.1
index 81626faa..8fd63dc4 100644
--- a/tmux.1
+++ b/tmux.1
@@ -851,6 +851,7 @@ option).
 The following keys are supported as appropriate for the mode:
 .Bl -column "FunctionXXXXXXXXXXXXXXXXX" "viXXXXXXXXXX" "emacs" -offset indent
 .It Sy "Function" Ta Sy "vi" Ta Sy "emacs"
+.It Li "Append selection" Ta "A" Ta ""
 .It Li "Back to indentation" Ta "^" Ta "M-m"
 .It Li "Bottom of history" Ta "G" Ta "M-<"
 .It Li "Clear selection" Ta "Escape" Ta "C-g"
@@ -3543,12 +3544,16 @@ The
 .Fl a
 option appends to rather than overwriting the file.
 .It Xo Ic set-buffer
+.Op Fl a
 .Op Fl b Ar buffer-index
 .Ar data
 .Xc
 .D1 (alias: Ic setb )
 Set the contents of the specified buffer to
 .Ar data .
+The
+.Fl a
+option appends to rather than overwriting the buffer.
 .It Xo Ic show-buffer
 .Op Fl b Ar buffer-index
 .Xc
diff --git a/tmux.h b/tmux.h
index fe4a697b..b30f2080 100644
--- a/tmux.h
+++ b/tmux.h
@@ -540,6 +540,7 @@ enum mode_key_cmd {
 	MODEKEYCHOICE_UP,
 
 	/* Copy keys. */
+	MODEKEYCOPY_APPENDSELECTION,
 	MODEKEYCOPY_BACKTOINDENTATION,
 	MODEKEYCOPY_BOTTOMLINE,
 	MODEKEYCOPY_CANCEL,
diff --git a/window-copy.c b/window-copy.c
index 76c9c3ce..7d7f3a20 100644
--- a/window-copy.c
+++ b/window-copy.c
@@ -58,6 +58,7 @@ void	window_copy_copy_buffer(struct window_pane *, int, void *, size_t);
 void	window_copy_copy_pipe(
 	    struct window_pane *, struct session *, int, const char *);
 void	window_copy_copy_selection(struct window_pane *, int);
+void	window_copy_append_selection(struct window_pane *, int);
 void	window_copy_clear_selection(struct window_pane *);
 void	window_copy_copy_line(
 	    struct window_pane *, char **, size_t *, u_int, u_int, u_int);
@@ -414,6 +415,13 @@ window_copy_key(struct window_pane *wp, struct session *sess, int key)
 
 	cmd = mode_key_lookup(&data->mdata, key, &arg);
 	switch (cmd) {
+	case MODEKEYCOPY_APPENDSELECTION:
+		if (sess != NULL) {
+			window_copy_append_selection(wp, data->numprefix);
+			window_pane_reset_mode(wp);
+			return;
+		}
+		break;
 	case MODEKEYCOPY_CANCEL:
 		window_pane_reset_mode(wp);
 		return;
@@ -1491,6 +1499,46 @@ window_copy_copy_selection(struct window_pane *wp, int idx)
 	window_copy_copy_buffer(wp, idx, buf, len);
 }
 
+void
+window_copy_append_selection(struct window_pane *wp, int idx)
+{
+	char			*buf;
+	struct paste_buffer	*pb;
+	size_t			 len;
+	u_int			 limit;
+	struct screen_write_ctx	 ctx;
+
+	buf = window_copy_get_selection(wp, &len);
+	if (buf == NULL)
+		return;
+
+	if (options_get_number(&global_options, "set-clipboard")) {
+		screen_write_start(&ctx, wp, NULL);
+		screen_write_setselection(&ctx, buf, len);
+		screen_write_stop(&ctx);
+	}
+
+	if (idx == -1)
+		idx = 0;
+
+	if (idx == 0 && paste_get_top(&global_buffers) == NULL) {
+		limit = options_get_number(&global_options, "buffer-limit");
+		paste_add(&global_buffers, buf, len, limit);
+		return;
+	}
+
+	pb = paste_get_index(&global_buffers, idx);
+	if (pb != NULL) {
+		buf = xrealloc(buf, 1, len + pb->size);
+		memmove(buf + pb->size, buf, len);
+		memcpy(buf, pb->data, pb->size);
+		len += pb->size;
+	}
+
+	if (paste_replace(&global_buffers, idx, buf, len) != 0)
+		free(buf);
+}
+
 void
 window_copy_copy_line(struct window_pane *wp,
     char **buf, size_t *off, u_int sy, u_int sx, u_int ex)