diff --git a/client.c b/client.c
index 5458dfc9..6d4b8a5a 100644
--- a/client.c
+++ b/client.c
@@ -557,7 +557,7 @@ client_dispatch_wait(void *data0)
 		data = imsg.data;
 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
 
-		log_debug("got %d from server", imsg.hdr.type);
+		log_debug("got %u from server", imsg.hdr.type);
 		switch (imsg.hdr.type) {
 		case MSG_EXIT:
 		case MSG_SHUTDOWN:
@@ -604,7 +604,7 @@ client_dispatch_wait(void *data0)
 				fatalx("bad MSG_VERSION size");
 
 			fprintf(stderr, "protocol version mismatch "
-			    "(client %u, server %u)\n", PROTOCOL_VERSION,
+			    "(client %d, server %u)\n", PROTOCOL_VERSION,
 			    imsg.hdr.peerid);
 			client_exitval = 1;
 
@@ -648,7 +648,7 @@ client_dispatch_attached(void)
 		data = imsg.data;
 		datalen = imsg.hdr.len - IMSG_HEADER_SIZE;
 
-		log_debug("got %d from server", imsg.hdr.type);
+		log_debug("got %u from server", imsg.hdr.type);
 		switch (imsg.hdr.type) {
 		case MSG_DETACH:
 		case MSG_DETACHKILL:
diff --git a/cmd-capture-pane.c b/cmd-capture-pane.c
index ce60b4c5..b44ebe9d 100644
--- a/cmd-capture-pane.c
+++ b/cmd-capture-pane.c
@@ -74,7 +74,7 @@ cmd_capture_pane_pending(struct args *args, struct window_pane *wp,
 				tmp[0] = line[i];
 				tmp[1] = '\0';
 			} else
-				xsnprintf(tmp, sizeof tmp, "\\%03o", line[i]);
+				xsnprintf(tmp, sizeof tmp, "\\%03hho", line[i]);
 			buf = cmd_capture_pane_append(buf, len, tmp,
 			    strlen(tmp));
 		}
diff --git a/cmd-respawn-pane.c b/cmd-respawn-pane.c
index 47031539..6575e8e4 100644
--- a/cmd-respawn-pane.c
+++ b/cmd-respawn-pane.c
@@ -59,7 +59,7 @@ cmd_respawn_pane_exec(struct cmd *self, struct cmd_q *cmdq)
 	if (!args_has(self->args, 'k') && wp->fd != -1) {
 		if (window_pane_index(wp, &idx) != 0)
 			fatalx("index not found");
-		cmdq_error(cmdq, "pane still active: %s:%u.%u",
+		cmdq_error(cmdq, "pane still active: %s:%d.%u",
 		    s->name, wl->idx, idx);
 		return (CMD_RETURN_ERROR);
 	}
diff --git a/colour.c b/colour.c
index b5efd6f1..82f8533a 100644
--- a/colour.c
+++ b/colour.c
@@ -147,7 +147,7 @@ colour_tostring(int c)
 	static char	s[32];
 
 	if (c & 0x100) {
-		xsnprintf(s, sizeof s, "colour%u", c & ~0x100);
+		xsnprintf(s, sizeof s, "colour%d", c & ~0x100);
 		return (s);
 	}
 
diff --git a/format.c b/format.c
index 01fa3ade..92271753 100644
--- a/format.c
+++ b/format.c
@@ -503,7 +503,7 @@ format_defaults_session(struct format_tree *ft, struct session *s)
 	format_add(ft, "session_created_string", "%s", tim);
 
 	format_add(ft, "session_attached", "%u", s->attached);
-	format_add(ft, "session_many_attached", "%u", s->attached > 1);
+	format_add(ft, "session_many_attached", "%d", s->attached > 1);
 }
 
 /* Set default format keys for a client. */
@@ -572,7 +572,7 @@ format_defaults_window(struct format_tree *ft, struct window *w)
 	format_add(ft, "window_height", "%u", w->sy);
 	format_add(ft, "window_layout", "%s", layout);
 	format_add(ft, "window_panes", "%u", window_count_panes(w));
-	format_add(ft, "window_zoomed_flag", "%u",
+	format_add(ft, "window_zoomed_flag", "%d",
 	    !!(w->flags & WINDOW_ZOOMED));
 
 	free(layout);
@@ -597,13 +597,13 @@ format_defaults_winlink(struct format_tree *ft, struct session *s,
 	format_add(ft, "window_flags", "%s", flags);
 	format_add(ft, "window_active", "%d", wl == s->curw);
 
-	format_add(ft, "window_bell_flag", "%u",
+	format_add(ft, "window_bell_flag", "%d",
 	    !!(wl->flags & WINLINK_BELL));
-	format_add(ft, "window_activity_flag", "%u",
+	format_add(ft, "window_activity_flag", "%d",
 	    !!(wl->flags & WINLINK_ACTIVITY));
-	format_add(ft, "window_silence_flag", "%u",
+	format_add(ft, "window_silence_flag", "%d",
 	    !!(wl->flags & WINLINK_SILENCE));
-	format_add(ft, "window_last_flag", "%u",
+	format_add(ft, "window_last_flag", "%d",
 	    !!(wl == TAILQ_FIRST(&s->lastw)));
 
 	free(flags);
@@ -623,7 +623,7 @@ format_defaults_pane_tabs(struct format_tree *ft, struct window_pane *wp)
 
 		if (EVBUFFER_LENGTH(buffer) > 0)
 			evbuffer_add(buffer, ",", 1);
-		evbuffer_add_printf(buffer, "%d", i);
+		evbuffer_add_printf(buffer, "%u", i);
 	}
 
 	format_add(ft, "pane_tabs", "%.*s", (int) EVBUFFER_LENGTH(buffer),
@@ -694,16 +694,16 @@ format_defaults_pane(struct format_tree *ft, struct window_pane *wp)
 		free(cmd);
 	}
 
-	format_add(ft, "cursor_x", "%d", wp->base.cx);
-	format_add(ft, "cursor_y", "%d", wp->base.cy);
-	format_add(ft, "scroll_region_upper", "%d", wp->base.rupper);
-	format_add(ft, "scroll_region_lower", "%d", wp->base.rlower);
-	format_add(ft, "saved_cursor_x", "%d", wp->ictx.old_cx);
-	format_add(ft, "saved_cursor_y", "%d", wp->ictx.old_cy);
+	format_add(ft, "cursor_x", "%u", wp->base.cx);
+	format_add(ft, "cursor_y", "%u", wp->base.cy);
+	format_add(ft, "scroll_region_upper", "%u", wp->base.rupper);
+	format_add(ft, "scroll_region_lower", "%u", wp->base.rlower);
+	format_add(ft, "saved_cursor_x", "%u", wp->ictx.old_cx);
+	format_add(ft, "saved_cursor_y", "%u", wp->ictx.old_cy);
 
 	format_add(ft, "alternate_on", "%d", wp->saved_grid ? 1 : 0);
-	format_add(ft, "alternate_saved_x", "%d", wp->saved_cx);
-	format_add(ft, "alternate_saved_y", "%d", wp->saved_cy);
+	format_add(ft, "alternate_saved_x", "%u", wp->saved_cx);
+	format_add(ft, "alternate_saved_y", "%u", wp->saved_cy);
 
 	format_add(ft, "cursor_flag", "%d",
 	    !!(wp->base.mode & MODE_CURSOR));
diff --git a/input-keys.c b/input-keys.c
index 040a0605..f2d010d8 100644
--- a/input-keys.c
+++ b/input-keys.c
@@ -219,7 +219,7 @@ input_mouse(struct window_pane *wp, struct session *s, struct mouse_event *m)
 		 * legacy format.
 		 */
 		if (m->sgr && (wp->screen->mode & MODE_MOUSE_SGR)) {
-			len = xsnprintf(buf, sizeof buf, "\033[<%d;%d;%d%c",
+			len = xsnprintf(buf, sizeof buf, "\033[<%u;%u;%u%c",
 			    m->sgr_xb, m->x + 1, m->y + 1,
 			    m->sgr_rel ? 'm' : 'M');
 		} else if (wp->screen->mode & MODE_MOUSE_UTF8) {
diff --git a/input.c b/input.c
index de11f629..9f7d4413 100644
--- a/input.c
+++ b/input.c
@@ -1717,7 +1717,7 @@ void
 input_exit_osc(struct input_ctx *ictx)
 {
 	u_char	*p = ictx->input_buf;
-	int	 option;
+	u_int	 option;
 
 	if (ictx->flags & INPUT_DISCARD)
 		return;
diff --git a/server-client.c b/server-client.c
index 280815cb..8373a0ef 100644
--- a/server-client.c
+++ b/server-client.c
@@ -824,7 +824,7 @@ server_client_msg_dispatch(struct client *c)
 			continue;
 		}
 
-		log_debug("got %d from client %d", imsg.hdr.type, c->ibuf.fd);
+		log_debug("got %u from client %d", imsg.hdr.type, c->ibuf.fd);
 		switch (imsg.hdr.type) {
 		case MSG_IDENTIFY_FLAGS:
 		case MSG_IDENTIFY_TERM:
diff --git a/server-fn.c b/server-fn.c
index b8cdb31a..f89eca8e 100644
--- a/server-fn.c
+++ b/server-fn.c
@@ -41,9 +41,9 @@ server_fill_environ(struct session *s, struct environ *env)
 
 		idx = s->id;
 	} else
-		idx = -1;
+		idx = (u_int)-1;
 	pid = getpid();
-	xsnprintf(var, sizeof var, "%s,%ld,%d", socket_path, pid, idx);
+	xsnprintf(var, sizeof var, "%s,%ld,%u", socket_path, pid, idx);
 	environ_set(env, "TMUX", var);
 }
 
diff --git a/server-window.c b/server-window.c
index a14c3150..a2355701 100644
--- a/server-window.c
+++ b/server-window.c
@@ -90,7 +90,7 @@ server_window_check_bell(struct session *s, struct winlink *wl)
 		if (c->session->curw->window == w)
 			status_message_set(c, "Bell in current window");
 		else if (action == BELL_ANY)
-			status_message_set(c, "Bell in window %u", wl->idx);
+			status_message_set(c, "Bell in window %d", wl->idx);
 	}
 
 	return (1);
@@ -124,7 +124,7 @@ server_window_check_activity(struct session *s, struct winlink *wl)
 			c = ARRAY_ITEM(&clients, i);
 			if (c == NULL || c->session != s)
 				continue;
-			status_message_set(c, "Activity in window %u", wl->idx);
+			status_message_set(c, "Activity in window %d", wl->idx);
 		}
 	}
 
@@ -175,7 +175,7 @@ server_window_check_silence(struct session *s, struct winlink *wl)
 			c = ARRAY_ITEM(&clients, i);
 			if (c == NULL || c->session != s)
 				continue;
-			status_message_set(c, "Silence in window %u", wl->idx);
+			status_message_set(c, "Silence in window %d", wl->idx);
 		}
 	}
 
diff --git a/window-choose.c b/window-choose.c
index 69141676..8bed8d45 100644
--- a/window-choose.c
+++ b/window-choose.c
@@ -98,7 +98,7 @@ window_choose_add(struct window_pane *wp, struct window_choose_data *wcd)
 	item->pos = ARRAY_LENGTH(&data->list) - 1;
 	item->state = 0;
 
-	data->width = xsnprintf(tmp, sizeof tmp , "%u", item->pos);
+	data->width = xsnprintf(tmp, sizeof tmp , "%d", item->pos);
 }
 
 void
diff --git a/window-copy.c b/window-copy.c
index 223df88a..074e7310 100644
--- a/window-copy.c
+++ b/window-copy.c
@@ -1216,7 +1216,7 @@ window_copy_write_line(struct window_pane *wp, struct screen_write_ctx *ctx,
 			limit = screen_size_x(s) + 1;
 		if (data->inputtype == WINDOW_COPY_NUMERICPREFIX) {
 			xoff = size = xsnprintf(hdr, limit,
-			    "Repeat: %u", data->numprefix);
+			    "Repeat: %d", data->numprefix);
 		} else {
 			xoff = size = xsnprintf(hdr, limit,
 			    "%s: %s", data->inputprompt, data->inputstr);