diff --git a/Makefile.am b/Makefile.am
index 1b9c092e..d85167b0 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -379,7 +379,6 @@ i3_nagbar_i3_nagbar_LDADD = \
 
 i3_nagbar_i3_nagbar_SOURCES = \
 	i3-nagbar/atoms.xmacro \
-	i3-nagbar/i3-nagbar.h \
 	i3-nagbar/main.c
 
 i3bar_i3bar_CPPFLAGS = \
diff --git a/generate-command-parser.pl b/generate-command-parser.pl
index a017edab..77502db7 100755
--- a/generate-command-parser.pl
+++ b/generate-command-parser.pl
@@ -117,6 +117,7 @@ my @keys = sort { (length($b) <=> length($a)) or ($a cmp $b) } keys %states;
 open(my $enumfh, '>', "GENERATED_${prefix}_enums.h");
 
 my %statenum;
+say $enumfh '#pragma once';
 say $enumfh 'typedef enum {';
 my $cnt = 0;
 for my $state (@keys, '__CALL') {
@@ -131,6 +132,7 @@ close($enumfh);
 # Third step: Generate the call function.
 open(my $callfh, '>', "GENERATED_${prefix}_call.h");
 my $resultname = uc(substr($prefix, 0, 1)) . substr($prefix, 1) . 'ResultIR';
+say $callfh '#pragma once';
 say $callfh "static void GENERATED_call(const int call_identifier, struct $resultname *result) {";
 say $callfh '    switch (call_identifier) {';
 my $call_id = 0;
@@ -206,6 +208,7 @@ close($callfh);
 # Fourth step: Generate the token datastructures.
 
 open(my $tokfh, '>', "GENERATED_${prefix}_tokens.h");
+say $tokfh '#pragma once';
 
 for my $state (@keys) {
     my $tokens = $states{$state};
diff --git a/i3-config-wizard/main.c b/i3-config-wizard/main.c
index f999de30..9e07d1f7 100644
--- a/i3-config-wizard/main.c
+++ b/i3-config-wizard/main.c
@@ -10,6 +10,8 @@
  */
 #include <config.h>
 
+#include "libi3.h"
+
 #if defined(__FreeBSD__)
 #include <sys/param.h>
 #endif
@@ -23,37 +25,31 @@
 #define _WITH_GETLINE
 #endif
 
-#include <stdio.h>
-#include <sys/types.h>
-#include <stdlib.h>
-#include <stdbool.h>
-#include <unistd.h>
-#include <string.h>
 #include <ctype.h>
-#include <errno.h>
 #include <err.h>
-#include <stdint.h>
+#include <errno.h>
+#include <fcntl.h>
 #include <getopt.h>
 #include <limits.h>
+#include <stdlib.h>
+#include <string.h>
 #include <sys/stat.h>
-#include <fcntl.h>
-#include <glob.h>
-#include <assert.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
 #include <xcb/xcb_event.h>
 #include <xcb/xcb_keysyms.h>
-
-#include <xkbcommon/xkbcommon.h>
 #include <xkbcommon/xkbcommon-x11.h>
+#include <xkbcommon/xkbcommon.h>
 
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launchee.h>
 
+#include <X11/XKBlib.h>
 #include <X11/Xlib.h>
 #include <X11/keysym.h>
-#include <X11/XKBlib.h>
 
 /* We need SYSCONFDIR for the path to the keycode config template, so raise an
  * error if it’s not defined for whatever reason */
@@ -69,7 +65,6 @@
 
 #include "xcb.h"
 xcb_visualtype_t *visual_type = NULL;
-#include "libi3.h"
 
 #define TEXT_PADDING logical_px(4)
 #define WIN_POS_X logical_px(490)
diff --git a/i3-dump-log/main.c b/i3-dump-log/main.c
index ba60d396..e58b0c37 100644
--- a/i3-dump-log/main.c
+++ b/i3-dump-log/main.c
@@ -9,27 +9,22 @@
  */
 #include <config.h>
 
-#include <stdio.h>
-#include <stdbool.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <errno.h>
-#include <err.h>
-#include <stdint.h>
-#include <getopt.h>
-#include <limits.h>
-#include <fcntl.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <signal.h>
-
 #include "libi3.h"
 #include "shmlog.h"
+
+#include <err.h>
+#include <fcntl.h>
+#include <getopt.h>
 #include <i3/ipc.h>
+#include <signal.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <unistd.h>
 
 #if !defined(__OpenBSD__)
 static uint32_t offset_next_write;
diff --git a/i3-input/keysym2ucs.c b/i3-input/keysym2ucs.c
index 52bdc044..80375099 100644
--- a/i3-input/keysym2ucs.c
+++ b/i3-input/keysym2ucs.c
@@ -31,9 +31,10 @@
  * This software is in the public domain. Share and enjoy!
  */
 
-#include <xcb/xcb.h>
 #include "keysym2ucs.h"
 
+#include <xcb/xcb.h>
+
 struct codepair {
     unsigned short keysym;
     unsigned short ucs;
diff --git a/i3-input/main.c b/i3-input/main.c
index e495fe10..dc38b8a6 100644
--- a/i3-input/main.c
+++ b/i3-input/main.c
@@ -8,32 +8,26 @@
  *                  to i3.
  *
  */
-#include <stdio.h>
-#include <sys/types.h>
-#include <stdlib.h>
-#include <stdbool.h>
-#include <unistd.h>
-#include <string.h>
-#include <errno.h>
-#include <err.h>
-#include <stdint.h>
 #include <getopt.h>
-#include <limits.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
 
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
-#include <xcb/xcb_event.h>
 #include <xcb/xcb_keysyms.h>
 
 xcb_visualtype_t *visual_type = NULL;
+#include "i3-input.h"
+#include "keysym2ucs.h"
 #include "libi3.h"
 
 #include <X11/keysym.h>
 
-#include "keysym2ucs.h"
-
-#include "i3-input.h"
-
 #define MAX_WIDTH logical_px(500)
 #define BORDER logical_px(2)
 #define PADDING logical_px(2)
diff --git a/i3-msg/main.c b/i3-msg/main.c
index 3a897416..0b0ef4e3 100644
--- a/i3-msg/main.c
+++ b/i3-msg/main.c
@@ -16,27 +16,17 @@
  */
 #include "libi3.h"
 
-#include <stdio.h>
-#include <stdbool.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <string.h>
-#include <errno.h>
 #include <err.h>
-#include <stdint.h>
 #include <getopt.h>
-#include <limits.h>
+#include <i3/ipc.h>
+#include <stdbool.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 
 #include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
-
-#include <xcb/xcb.h>
-#include <xcb/xcb_aux.h>
-
-#include <i3/ipc.h>
 
 /*
  * Having verboselog() and errorlog() is necessary when using libi3.
diff --git a/i3-nagbar/i3-nagbar.h b/i3-nagbar/i3-nagbar.h
deleted file mode 100644
index cb672bea..00000000
--- a/i3-nagbar/i3-nagbar.h
+++ /dev/null
@@ -1,18 +0,0 @@
-#pragma once
-
-#include <config.h>
-
-#include <err.h>
-
-#define die(...) errx(EXIT_FAILURE, __VA_ARGS__);
-#define FREE(pointer)   \
-    do {                \
-        free(pointer);  \
-        pointer = NULL; \
-    } while (0)
-
-#define xmacro(atom) xcb_atom_t A_##atom;
-#include "atoms.xmacro"
-#undef xmacro
-
-extern xcb_window_t root;
diff --git a/i3-nagbar/main.c b/i3-nagbar/main.c
index e59f5a6a..51e5475c 100644
--- a/i3-nagbar/main.c
+++ b/i3-nagbar/main.c
@@ -8,36 +8,33 @@
  * when the user has an error in their configuration file.
  *
  */
-#include <stdio.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/wait.h>
-#include <stdlib.h>
-#include <stdbool.h>
-#include <unistd.h>
-#include <string.h>
-#include <errno.h>
+#include <config.h>
+
+#include "libi3.h"
+
 #include <err.h>
-#include <stdint.h>
+#include <fcntl.h>
 #include <getopt.h>
 #include <limits.h>
-#include <fcntl.h>
 #include <paths.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <unistd.h>
 
+#include <xcb/randr.h>
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
-#include <xcb/xcb_event.h>
-#include <xcb/randr.h>
 #include <xcb/xcb_cursor.h>
 
 xcb_visualtype_t *visual_type = NULL;
-#include "libi3.h"
 
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launchee.h>
 
-#include "i3-nagbar.h"
-
 #define MSG_PADDING logical_px(8)
 #define BTN_PADDING logical_px(3)
 #define BTN_BORDER logical_px(3)
@@ -45,6 +42,12 @@ xcb_visualtype_t *visual_type = NULL;
 #define CLOSE_BTN_GAP logical_px(15)
 #define BAR_BORDER logical_px(2)
 
+#define xmacro(atom) xcb_atom_t A_##atom;
+#include "atoms.xmacro"
+#undef xmacro
+
+#define die(...) errx(EXIT_FAILURE, __VA_ARGS__);
+
 static char *argv0 = NULL;
 
 typedef struct {
@@ -314,8 +317,8 @@ static xcb_rectangle_t get_window_position(void) {
     goto free_resources;
 
 free_resources:
-    FREE(res);
-    FREE(primary);
+    free(res);
+    free(primary);
     return result;
 }
 
@@ -598,7 +601,7 @@ int main(int argc, char *argv[]) {
         free(event);
     }
 
-    FREE(pattern);
+    free(pattern);
     draw_util_surface_free(conn, &bar);
 
     return 0;
diff --git a/i3bar/include/common.h b/i3bar/include/common.h
index 222f42dd..2d763133 100644
--- a/i3bar/include/common.h
+++ b/i3bar/include/common.h
@@ -9,7 +9,6 @@
 
 #include <config.h>
 
-#include <stdbool.h>
 #include <xcb/xcb.h>
 #include <xcb/xproto.h>
 #include "libi3.h"
@@ -94,5 +93,4 @@ extern TAILQ_HEAD(statusline_head, status_block)
 #include "trayclients.h"
 #include "xcb.h"
 #include "configuration.h"
-#include "libi3.h"
 #include "parse_json_header.h"
diff --git a/i3bar/src/child.c b/i3bar/src/child.c
index e56145fa..871c2305 100644
--- a/i3bar/src/child.c
+++ b/i3bar/src/child.c
@@ -10,25 +10,21 @@
 #include "common.h"
 #include "yajl_utils.h"
 
-#include <stdlib.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include <sys/wait.h>
-#include <signal.h>
-#include <stdio.h>
-#include <stdarg.h>
-#include <fcntl.h>
-#include <string.h>
-#include <errno.h>
 #include <err.h>
+#include <errno.h>
 #include <ev.h>
-#include <yajl/yajl_common.h>
-#include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
-#include <yajl/yajl_gen.h>
+#include <fcntl.h>
 #include <paths.h>
+#include <signal.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/wait.h>
+#include <unistd.h>
 
-#include <xcb/xcb_keysyms.h>
+#include <yajl/yajl_gen.h>
+#include <yajl/yajl_parse.h>
 
 /* Global variables for child_*() */
 i3bar_child child;
diff --git a/i3bar/src/config.c b/i3bar/src/config.c
index 29b0908b..5d4bf88a 100644
--- a/i3bar/src/config.c
+++ b/i3bar/src/config.c
@@ -9,15 +9,12 @@
  */
 #include "common.h"
 
-#include <string.h>
-#include <stdlib.h>
 #include <stdio.h>
-#include <errno.h>
-#include <i3/ipc.h>
-#include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include <X11/Xlib.h>
+#include <yajl/yajl_parse.h>
 
 config_t config;
 static char *cur_key;
diff --git a/i3bar/src/ipc.c b/i3bar/src/ipc.c
index 37bdbac2..f2c105ac 100644
--- a/i3bar/src/ipc.c
+++ b/i3bar/src/ipc.c
@@ -9,16 +9,13 @@
  */
 #include "common.h"
 
-#include <stdlib.h>
-#include <stdio.h>
-#include <unistd.h>
-#include <stdint.h>
-#include <string.h>
 #include <errno.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <i3/ipc.h>
 #include <ev.h>
+#include <i3/ipc.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 #ifdef I3_ASAN_ENABLED
 #include <sanitizer/lsan_interface.h>
 #endif
diff --git a/i3bar/src/main.c b/i3bar/src/main.c
index 65cb00ff..4e729341 100644
--- a/i3bar/src/main.c
+++ b/i3bar/src/main.c
@@ -7,15 +7,13 @@
  */
 #include "common.h"
 
-#include <stdio.h>
-#include <i3/ipc.h>
-#include <string.h>
-#include <unistd.h>
-#include <stdlib.h>
-#include <errno.h>
 #include <ev.h>
 #include <getopt.h>
 #include <glob.h>
+#include <i3/ipc.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 
 struct ev_loop *main_loop;
 
diff --git a/i3bar/src/mode.c b/i3bar/src/mode.c
index 97087ce0..13d02110 100644
--- a/i3bar/src/mode.c
+++ b/i3bar/src/mode.c
@@ -9,12 +9,10 @@
  */
 #include "common.h"
 
-#include <string.h>
 #include <stdlib.h>
-#include <stdio.h>
-#include <errno.h>
+#include <string.h>
+
 #include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
 
 /* A datatype to pass through the callbacks to save the state */
 struct mode_json_params {
diff --git a/i3bar/src/outputs.c b/i3bar/src/outputs.c
index 6ebb7cc6..46b9c954 100644
--- a/i3bar/src/outputs.c
+++ b/i3bar/src/outputs.c
@@ -9,13 +9,12 @@
  */
 #include "common.h"
 
-#include <string.h>
-#include <stdlib.h>
-#include <stdio.h>
 #include <errno.h>
-#include <i3/ipc.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
 #include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
 
 /* A datatype to pass through the callbacks to save the state */
 struct outputs_json_params {
diff --git a/i3bar/src/parse_json_header.c b/i3bar/src/parse_json_header.c
index 3d4c2a67..c74a62fe 100644
--- a/i3bar/src/parse_json_header.c
+++ b/i3bar/src/parse_json_header.c
@@ -10,22 +10,10 @@
  */
 #include "common.h"
 
-#include <stdlib.h>
-#include <unistd.h>
-#include <sys/types.h>
-#include <sys/wait.h>
 #include <signal.h>
-#include <stdio.h>
-#include <fcntl.h>
 #include <string.h>
-#include <errno.h>
-#include <err.h>
-#include <ev.h>
-#include <stdbool.h>
-#include <stdint.h>
-#include <yajl/yajl_common.h>
+
 #include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
 
 static enum {
     KEY_VERSION,
diff --git a/i3bar/src/workspaces.c b/i3bar/src/workspaces.c
index 68686611..bd56f5d0 100644
--- a/i3bar/src/workspaces.c
+++ b/i3bar/src/workspaces.c
@@ -9,12 +9,10 @@
  */
 #include "common.h"
 
-#include <string.h>
 #include <stdlib.h>
-#include <stdio.h>
-#include <errno.h>
+#include <string.h>
+
 #include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
 
 /* A datatype to pass through the callbacks to save the state */
 struct workspaces_json_params {
diff --git a/i3bar/src/xcb.c b/i3bar/src/xcb.c
index ecb41a60..5241f141 100644
--- a/i3bar/src/xcb.c
+++ b/i3bar/src/xcb.c
@@ -9,26 +9,15 @@
  */
 #include "common.h"
 
-#include <xcb/xcb.h>
-#include <xcb/xkb.h>
-#include <xcb/xproto.h>
+#include <err.h>
+#include <ev.h>
+#include <i3/ipc.h>
+#include <stdlib.h>
+#include <string.h>
+
 #include <xcb/xcb_aux.h>
 #include <xcb/xcb_cursor.h>
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <string.h>
-#include <i3/ipc.h>
-#include <ev.h>
-#include <errno.h>
-#include <limits.h>
-#include <err.h>
-
-#include <X11/Xlib.h>
-#include <X11/XKBlib.h>
-#include <X11/extensions/XKB.h>
+#include <xcb/xkb.h>
 
 #ifdef I3_ASAN_ENABLED
 #include <sanitizer/lsan_interface.h>
diff --git a/include/all.h b/include/all.h
index aa2b5b25..55111944 100644
--- a/include/all.h
+++ b/include/all.h
@@ -15,31 +15,24 @@
 #include <config.h>
 
 #include <assert.h>
+#include <err.h>
+#include <errno.h>
+#include <limits.h>
+#include <stdarg.h>
 #include <stdbool.h>
-#include <stdlib.h>
+#include <stdint.h>
 #include <stdio.h>
+#include <stdlib.h>
 #include <string.h>
-#include <locale.h>
-#include <getopt.h>
-#include <unistd.h>
 #include <sys/stat.h>
 #include <sys/types.h>
-#include <glob.h>
-#include <errno.h>
-#include <err.h>
-#include <stdint.h>
-#include <inttypes.h>
-#include <math.h>
-#include <limits.h>
 
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
-#include <xcb/xcb_keysyms.h>
 #include <xcb/xcb_icccm.h>
+#include <xcb/xcb_keysyms.h>
 
-#include <yajl/yajl_gen.h>
-#include <yajl/yajl_version.h>
-
+#include "libi3.h"
 #include "data.h"
 #include "util.h"
 #include "ipc.h"
@@ -72,7 +65,6 @@
 #include "ewmh.h"
 #include "assignments.h"
 #include "regex.h"
-#include "libi3.h"
 #include "startup.h"
 #include "scratchpad.h"
 #include "commands.h"
diff --git a/include/configuration.h b/include/configuration.h
index d7c2ab8b..eae36057 100644
--- a/include/configuration.h
+++ b/include/configuration.h
@@ -12,9 +12,6 @@
  */
 #pragma once
 
-#include "libi3.h"
-
-#include <stdbool.h>
 #include "queue.h"
 #include "i3.h"
 
diff --git a/include/data.h b/include/data.h
index e686d2c7..494dbe0a 100644
--- a/include/data.h
+++ b/include/data.h
@@ -9,13 +9,10 @@
  */
 #pragma once
 
-#include "libi3.h"
-
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launcher.h>
 
 #include <xcb/randr.h>
-#include <stdbool.h>
 #include <pcre.h>
 #include <sys/time.h>
 
diff --git a/include/ipc.h b/include/ipc.h
index 8ea9fd2e..bc5929ec 100644
--- a/include/ipc.h
+++ b/include/ipc.h
@@ -12,7 +12,6 @@
 #include <config.h>
 
 #include <ev.h>
-#include <stdbool.h>
 #include <yajl/yajl_gen.h>
 #include <yajl/yajl_parse.h>
 
diff --git a/include/log.h b/include/log.h
index 5c530231..d3c3e3f3 100644
--- a/include/log.h
+++ b/include/log.h
@@ -11,9 +11,6 @@
 
 #include <config.h>
 
-#include <stdarg.h>
-#include <stdbool.h>
-
 /* We will include libi3.h which define its own version of LOG, ELOG.
  * We want *our* version, so we undef the libi3 one. */
 #if defined(LOG)
diff --git a/include/shmlog.h b/include/shmlog.h
index dc8081f1..7b7e133a 100644
--- a/include/shmlog.h
+++ b/include/shmlog.h
@@ -12,7 +12,6 @@
 
 #include <config.h>
 
-#include <stdint.h>
 #if !defined(__OpenBSD__)
 #include <pthread.h>
 #endif
diff --git a/include/xinerama.h b/include/xinerama.h
index f01ee568..52a5db33 100644
--- a/include/xinerama.h
+++ b/include/xinerama.h
@@ -13,8 +13,6 @@
 
 #include <config.h>
 
-#include "data.h"
-
 /**
  * We have just established a connection to the X server and need the initial
  * Xinerama information to setup workspaces for each screen.
diff --git a/libi3/dpi.c b/libi3/dpi.c
index d15e35be..dec38bc8 100644
--- a/libi3/dpi.c
+++ b/libi3/dpi.c
@@ -9,6 +9,7 @@
 
 #include <math.h>
 #include <stdlib.h>
+
 #include <xcb/xcb_xrm.h>
 
 static long dpi;
diff --git a/libi3/draw_util.c b/libi3/draw_util.c
index 092ac967..313dc29a 100644
--- a/libi3/draw_util.c
+++ b/libi3/draw_util.c
@@ -9,11 +9,10 @@
 #include "libi3.h"
 
 #include <stdlib.h>
-#include <err.h>
 #include <string.h>
+
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
-#include <cairo/cairo-xcb.h>
 
 /* The default visual_type to use if none is specified when creating the surface. Must be defined globally. */
 extern xcb_visualtype_t *visual_type;
diff --git a/libi3/fake_configure_notify.c b/libi3/fake_configure_notify.c
index 145f4512..5d87c3da 100644
--- a/libi3/fake_configure_notify.c
+++ b/libi3/fake_configure_notify.c
@@ -8,7 +8,6 @@
 #include "libi3.h"
 
 #include <stdlib.h>
-#include <stdbool.h>
 
 #include <xcb/xcb.h>
 #include <xcb/xproto.h>
diff --git a/libi3/font.c b/libi3/font.c
index 7b10edf0..5ed58b8d 100644
--- a/libi3/font.c
+++ b/libi3/font.c
@@ -8,14 +8,12 @@
 #include "libi3.h"
 
 #include <assert.h>
+#include <cairo/cairo-xcb.h>
+#include <err.h>
+#include <pango/pangocairo.h>
 #include <stdint.h>
 #include <stdlib.h>
 #include <string.h>
-#include <stdbool.h>
-#include <err.h>
-
-#include <cairo/cairo-xcb.h>
-#include <pango/pangocairo.h>
 
 static const i3Font *savedFont = NULL;
 
diff --git a/libi3/format_placeholders.c b/libi3/format_placeholders.c
index 770e383d..71870a7b 100644
--- a/libi3/format_placeholders.c
+++ b/libi3/format_placeholders.c
@@ -8,7 +8,6 @@
 #include "libi3.h"
 
 #include <stdlib.h>
-#include <stdint.h>
 #include <string.h>
 
 #ifndef CS_STARTS_WITH
diff --git a/libi3/g_utf8_make_valid.c b/libi3/g_utf8_make_valid.c
index b15873b3..71beafd3 100644
--- a/libi3/g_utf8_make_valid.c
+++ b/libi3/g_utf8_make_valid.c
@@ -19,8 +19,8 @@
 
 #include "libi3.h"
 
-#include <string.h>
 #include <glib.h>
+#include <string.h>
 
 /* Copied from:
  * https://gitlab.gnome.org/GNOME/glib/blob/f928dfdf57bf92c883b53b16d7a9d49add504f52/glib/gutf8.c#L1752-1815 */
diff --git a/libi3/get_colorpixel.c b/libi3/get_colorpixel.c
index 45931051..b60ffbac 100644
--- a/libi3/get_colorpixel.c
+++ b/libi3/get_colorpixel.c
@@ -6,12 +6,11 @@
  *
  */
 #include "libi3.h"
-
-#include <stdlib.h>
-#include <stdint.h>
-#include <string.h>
-
 #include "queue.h"
+
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
 struct Colorpixel {
     char hex[8];
     uint32_t pixel;
diff --git a/libi3/get_exe_path.c b/libi3/get_exe_path.c
index 430fb2e0..3b46ef82 100644
--- a/libi3/get_exe_path.c
+++ b/libi3/get_exe_path.c
@@ -7,12 +7,10 @@
  */
 #include "libi3.h"
 
-#include <unistd.h>
-#include <string.h>
-#include <stdio.h>
-#include <limits.h>
-#include <stdlib.h>
 #include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 
 /*
  * This function returns the absolute path to the executable it is running in.
diff --git a/libi3/get_mod_mask.c b/libi3/get_mod_mask.c
index 98031d4c..92af456d 100644
--- a/libi3/get_mod_mask.c
+++ b/libi3/get_mod_mask.c
@@ -9,6 +9,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+
 #include <xcb/xcb.h>
 #include <xcb/xcb_keysyms.h>
 
diff --git a/libi3/get_process_filename.c b/libi3/get_process_filename.c
index 7e2ecbd2..21429ec3 100644
--- a/libi3/get_process_filename.c
+++ b/libi3/get_process_filename.c
@@ -7,17 +7,11 @@
  */
 #include "libi3.h"
 
-#include <assert.h>
-#include <stdint.h>
-#include <stdlib.h>
-#include <string.h>
-#include <stdbool.h>
 #include <err.h>
-#include <sys/stat.h>
-#include <sys/types.h>
 #include <pwd.h>
+#include <stdlib.h>
+#include <sys/stat.h>
 #include <unistd.h>
-#include <err.h>
 
 /*
  * Returns the name of a temporary file with the specified prefix.
diff --git a/libi3/ipc_connect.c b/libi3/ipc_connect.c
index f659a1a4..871fe083 100644
--- a/libi3/ipc_connect.c
+++ b/libi3/ipc_connect.c
@@ -7,14 +7,12 @@
  */
 #include "libi3.h"
 
-#include <sys/types.h>
+#include <err.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
 #include <sys/socket.h>
 #include <sys/un.h>
-#include <string.h>
-#include <err.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <fcntl.h>
 
 /*
  * Connects to the i3 IPC socket and returns the file descriptor for the
diff --git a/libi3/ipc_recv_message.c b/libi3/ipc_recv_message.c
index 84da5aa3..516405b0 100644
--- a/libi3/ipc_recv_message.c
+++ b/libi3/ipc_recv_message.c
@@ -7,15 +7,12 @@
  */
 #include "libi3.h"
 
-#include <string.h>
-#include <stdlib.h>
-#include <stdio.h>
-#include <stdint.h>
-#include <unistd.h>
 #include <errno.h>
-#include <inttypes.h>
-
 #include <i3/ipc.h>
+#include <inttypes.h>
+#include <stdint.h>
+#include <string.h>
+#include <unistd.h>
 
 /*
  * Reads a message from the given socket file descriptor and stores its length
diff --git a/libi3/ipc_send_message.c b/libi3/ipc_send_message.c
index c2cc0127..4faeea7f 100644
--- a/libi3/ipc_send_message.c
+++ b/libi3/ipc_send_message.c
@@ -7,14 +7,8 @@
  */
 #include "libi3.h"
 
-#include <string.h>
-#include <stdlib.h>
-#include <unistd.h>
-#include <stdint.h>
-#include <err.h>
-#include <errno.h>
-
 #include <i3/ipc.h>
+#include <stdint.h>
 
 /*
  * Formats a message (payload) of the given size and type and sends it to i3 via
diff --git a/libi3/is_debug_build.c b/libi3/is_debug_build.c
index 52187bda..cb53407e 100644
--- a/libi3/is_debug_build.c
+++ b/libi3/is_debug_build.c
@@ -8,7 +8,6 @@
 #include "libi3.h"
 
 #include <string.h>
-#include <stdbool.h>
 
 /*
  * Returns true if this version of i3 is a debug build (anything which is not a
diff --git a/libi3/root_atom_contents.c b/libi3/root_atom_contents.c
index d6394d4b..6feb31bc 100644
--- a/libi3/root_atom_contents.c
+++ b/libi3/root_atom_contents.c
@@ -7,12 +7,9 @@
  */
 #include "libi3.h"
 
-#include <stdio.h>
-#include <string.h>
-#include <stdbool.h>
-#include <limits.h>
-#include <stdlib.h>
 #include <math.h>
+#include <stdlib.h>
+#include <string.h>
 
 #include <xcb/xcb.h>
 #include <xcb/xcb_aux.h>
diff --git a/libi3/safewrappers.c b/libi3/safewrappers.c
index fdea636e..767a0f05 100644
--- a/libi3/safewrappers.c
+++ b/libi3/safewrappers.c
@@ -7,13 +7,11 @@
  */
 #include "libi3.h"
 
-#include <string.h>
-#include <stdlib.h>
-#include <stdarg.h>
-#include <unistd.h>
-#include <stdio.h>
 #include <err.h>
 #include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
 
 /*
  * The s* functions (safe) are wrappers around malloc, strdup, …, which exits if one of
diff --git a/libi3/string.c b/libi3/string.c
index 9efa3690..da18c550 100644
--- a/libi3/string.c
+++ b/libi3/string.c
@@ -11,11 +11,10 @@
  */
 #include "libi3.h"
 
+#include <glib.h>
 #include <stdlib.h>
 #include <string.h>
 
-#include <glib.h>
-
 struct _i3String {
     char *utf8;
     xcb_char2b_t *ucs2;
diff --git a/libi3/strndup.c b/libi3/strndup.c
index e215a76f..a0e87cf6 100644
--- a/libi3/strndup.c
+++ b/libi3/strndup.c
@@ -7,7 +7,6 @@
  */
 #include "libi3.h"
 
-#include <sys/types.h>
 #include <string.h>
 
 #ifndef HAVE_strndup
diff --git a/libi3/ucs2_conversion.c b/libi3/ucs2_conversion.c
index c651cdb3..c7467239 100644
--- a/libi3/ucs2_conversion.c
+++ b/libi3/ucs2_conversion.c
@@ -8,7 +8,6 @@
 #include "libi3.h"
 
 #include <err.h>
-#include <errno.h>
 #include <iconv.h>
 #include <stdlib.h>
 #include <string.h>
diff --git a/src/bindings.c b/src/bindings.c
index 03dc2306..e29f2c2d 100644
--- a/src/bindings.c
+++ b/src/bindings.c
@@ -8,8 +8,10 @@
  */
 #include "all.h"
 
-#include <xkbcommon/xkbcommon.h>
+#include <math.h>
+
 #include <xkbcommon/xkbcommon-x11.h>
+#include <xkbcommon/xkbcommon.h>
 
 static struct xkb_context *xkb_context;
 static struct xkb_keymap *xkb_keymap;
diff --git a/src/click.c b/src/click.c
index 12e391b5..64d78315 100644
--- a/src/click.c
+++ b/src/click.c
@@ -10,11 +10,6 @@
 #include "all.h"
 
 #include <time.h>
-#include <math.h>
-
-#include <xcb/xcb_icccm.h>
-
-#include <X11/XKBlib.h>
 
 typedef enum { CLICK_BORDER = 0,
                CLICK_DECORATION = 1,
diff --git a/src/commands.c b/src/commands.c
index d2024652..fa15c33f 100644
--- a/src/commands.c
+++ b/src/commands.c
@@ -8,15 +8,12 @@
  *
  */
 #include "all.h"
-
-#include <stdint.h>
-#include <float.h>
-#include <stdarg.h>
-#include <unistd.h>
-#include <fcntl.h>
-
 #include "shmlog.h"
 
+#include <fcntl.h>
+#include <stdint.h>
+#include <unistd.h>
+
 // Macros to make the YAJL API a bit easier to use.
 #define y(x, ...) (cmd_output->json_gen != NULL ? yajl_gen_##x(cmd_output->json_gen, ##__VA_ARGS__) : 0)
 #define ystr(str) (cmd_output->json_gen != NULL ? yajl_gen_string(cmd_output->json_gen, (unsigned char *)str, strlen(str)) : 0)
diff --git a/src/commands_parser.c b/src/commands_parser.c
index 2fd76309..6c791415 100644
--- a/src/commands_parser.c
+++ b/src/commands_parser.c
@@ -25,13 +25,6 @@
  */
 #include "all.h"
 
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <stdbool.h>
-#include <stdint.h>
-
 // Macros to make the YAJL API a bit easier to use.
 #define y(x, ...) (command_output.json_gen != NULL ? yajl_gen_##x(command_output.json_gen, ##__VA_ARGS__) : 0)
 #define ystr(str) (command_output.json_gen != NULL ? yajl_gen_string(command_output.json_gen, (unsigned char *)str, strlen(str)) : 0)
diff --git a/src/con.c b/src/con.c
index 08bb7e4e..d9a79221 100644
--- a/src/con.c
+++ b/src/con.c
@@ -10,7 +10,6 @@
  *
  */
 #include "all.h"
-
 #include "yajl_utils.h"
 
 static void con_on_remove_child(Con *con);
diff --git a/src/config_directives.c b/src/config_directives.c
index 4f9e415f..c039e35f 100644
--- a/src/config_directives.c
+++ b/src/config_directives.c
@@ -9,9 +9,6 @@
  */
 #include "all.h"
 
-#include <float.h>
-#include <stdarg.h>
-
 /*******************************************************************************
  * Criteria functions.
  ******************************************************************************/
diff --git a/src/config_parser.c b/src/config_parser.c
index f120cfa3..f78e75f8 100644
--- a/src/config_parser.c
+++ b/src/config_parser.c
@@ -25,16 +25,17 @@
  */
 #include "all.h"
 
+#include <fcntl.h>
+#include <stdbool.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
-#include <unistd.h>
-#include <stdbool.h>
-#include <stdint.h>
+#include <sys/stat.h>
 #include <sys/types.h>
 #include <sys/wait.h>
-#include <sys/stat.h>
-#include <fcntl.h>
+#include <unistd.h>
+
 #include <xcb/xcb_xrm.h>
 
 // Macros to make the YAJL API a bit easier to use.
diff --git a/src/display_version.c b/src/display_version.c
index e44540e0..32250c15 100644
--- a/src/display_version.c
+++ b/src/display_version.c
@@ -10,13 +10,9 @@
  */
 #include "all.h"
 
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/wait.h>
-#include <sys/socket.h>
-#include <sys/un.h>
 #include <fcntl.h>
 #include <time.h>
+#include <unistd.h>
 
 static bool human_readable_key, loaded_config_file_name_key;
 static char *human_readable_version, *loaded_config_file_name;
diff --git a/src/floating.c b/src/floating.c
index 4fed43e4..5e60aa82 100644
--- a/src/floating.c
+++ b/src/floating.c
@@ -9,6 +9,8 @@
  */
 #include "all.h"
 
+#include <math.h>
+
 #ifndef MAX
 #define MAX(x, y) ((x) > (y) ? (x) : (y))
 #endif
diff --git a/src/handlers.c b/src/handlers.c
index d6d6e20b..fa892cc4 100644
--- a/src/handlers.c
+++ b/src/handlers.c
@@ -10,9 +10,9 @@
  */
 #include "all.h"
 
-#include <time.h>
-#include <float.h>
 #include <sys/time.h>
+#include <time.h>
+
 #include <xcb/randr.h>
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-monitor.h>
diff --git a/src/ipc.c b/src/ipc.c
index 75fa8ee7..e616a53e 100644
--- a/src/ipc.c
+++ b/src/ipc.c
@@ -7,16 +7,19 @@
  * ipc.c: UNIX domain socket IPC (initialization, client handling, protocol).
  *
  */
-#include "all.h"
 
+#include "all.h"
 #include "yajl_utils.h"
 
+#include <ev.h>
+#include <fcntl.h>
+#include <libgen.h>
+#include <locale.h>
 #include <stdint.h>
 #include <sys/socket.h>
 #include <sys/un.h>
-#include <fcntl.h>
-#include <libgen.h>
-#include <ev.h>
+#include <unistd.h>
+
 #include <yajl/yajl_gen.h>
 #include <yajl/yajl_parse.h>
 
diff --git a/src/load_layout.c b/src/load_layout.c
index b69b388c..c0be3f26 100644
--- a/src/load_layout.c
+++ b/src/load_layout.c
@@ -10,10 +10,9 @@
  */
 #include "all.h"
 
-#include <yajl/yajl_common.h>
-#include <yajl/yajl_gen.h>
+#include <locale.h>
+
 #include <yajl/yajl_parse.h>
-#include <yajl/yajl_version.h>
 
 /* TODO: refactor the whole parsing thing */
 
diff --git a/src/log.c b/src/log.c
index 31db8b33..326f82b8 100644
--- a/src/log.c
+++ b/src/log.c
@@ -9,27 +9,24 @@
  */
 #include <config.h>
 
-#include <stdarg.h>
-#include <stdio.h>
-#include <string.h>
-#include <stdbool.h>
-#include <stdlib.h>
-#include <sys/time.h>
-#include <unistd.h>
+#include "all.h"
+#include "shmlog.h"
+
+#include <errno.h>
 #include <fcntl.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
-#include <errno.h>
+#include <sys/time.h>
+#include <unistd.h>
 #if !defined(__OpenBSD__)
 #include <pthread.h>
 #endif
 
-#include "util.h"
-#include "log.h"
-#include "i3.h"
-#include "libi3.h"
-#include "shmlog.h"
-
 #if defined(__APPLE__)
 #include <sys/sysctl.h>
 #endif
diff --git a/src/main.c b/src/main.c
index 369f2f66..4f4c3fd6 100644
--- a/src/main.c
+++ b/src/main.c
@@ -8,18 +8,22 @@
  *
  */
 #include "all.h"
+#include "shmlog.h"
 
 #include <ev.h>
 #include <fcntl.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <sys/time.h>
-#include <sys/resource.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
+#include <getopt.h>
 #include <libgen.h>
-#include "shmlog.h"
+#include <locale.h>
+#include <signal.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
 
 #ifdef I3_ASAN_ENABLED
 #include <sanitizer/lsan_interface.h>
diff --git a/src/manage.c b/src/manage.c
index eecba95c..5f860d4a 100644
--- a/src/manage.c
+++ b/src/manage.c
@@ -9,10 +9,6 @@
  */
 #include "all.h"
 
-#include "yajl_utils.h"
-
-#include <yajl/yajl_gen.h>
-
 /*
  * Match frame and window depth. This is needed because X will refuse to reparent a
  * window whose background is ParentRelative under a window with a different depth.
diff --git a/src/randr.c b/src/randr.c
index b163eca7..56b0707f 100644
--- a/src/randr.c
+++ b/src/randr.c
@@ -12,6 +12,7 @@
 #include "all.h"
 
 #include <time.h>
+
 #include <xcb/randr.h>
 
 /* Pointer to the result of the query for primary output */
diff --git a/src/render.c b/src/render.c
index 40704f52..bf96e4df 100644
--- a/src/render.c
+++ b/src/render.c
@@ -10,6 +10,8 @@
  */
 #include "all.h"
 
+#include <math.h>
+
 /* Forward declarations */
 static int *precalculate_sizes(Con *con, render_params *p);
 static void render_root(Con *con, Con *fullscreen);
diff --git a/src/sd-daemon.c b/src/sd-daemon.c
index 28a88bfd..84761025 100644
--- a/src/sd-daemon.c
+++ b/src/sd-daemon.c
@@ -28,22 +28,22 @@
 #define _GNU_SOURCE
 #endif
 
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <sys/fcntl.h>
-#include <netinet/in.h>
-#include <stdlib.h>
-#include <errno.h>
-#include <unistd.h>
-#include <string.h>
-#include <stdarg.h>
-#include <stdio.h>
-#include <stddef.h>
-
 #include "sd-daemon.h"
 
+#include <errno.h>
+#include <netinet/in.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/fcntl.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <unistd.h>
+
 int sd_listen_fds(int unset_environment) {
     int r, fd;
     const char *e;
diff --git a/src/sighandler.c b/src/sighandler.c
index 86921b40..c1e6094f 100644
--- a/src/sighandler.c
+++ b/src/sighandler.c
@@ -7,14 +7,9 @@
  */
 #include "all.h"
 
-#include <ev.h>
-#include <iconv.h>
 #include <signal.h>
 #include <sys/wait.h>
-
-#include <xcb/xcb_event.h>
-
-#include <X11/keysym.h>
+#include <unistd.h>
 
 typedef struct dialog_t {
     xcb_window_t id;
diff --git a/src/startup.c b/src/startup.c
index e994e0a8..9b0576e8 100644
--- a/src/startup.c
+++ b/src/startup.c
@@ -11,12 +11,12 @@
  *
  */
 #include "all.h"
-
 #include "sd-daemon.h"
 
+#include <paths.h>
 #include <sys/types.h>
 #include <sys/wait.h>
-#include <paths.h>
+#include <unistd.h>
 
 #define SN_API_NOT_YET_FROZEN 1
 #include <libsn/sn-launcher.h>
diff --git a/src/util.c b/src/util.c
index 3544297c..6d8d2ee7 100644
--- a/src/util.c
+++ b/src/util.c
@@ -10,19 +10,16 @@
  */
 #include "all.h"
 
+#include <ctype.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <libgen.h>
+#include <locale.h>
 #include <sys/wait.h>
-#include <stdarg.h>
+#include <unistd.h>
 #if defined(__OpenBSD__)
 #include <sys/cdefs.h>
 #endif
-#include <fcntl.h>
-#include <pwd.h>
-#include <yajl/yajl_version.h>
-#include <libgen.h>
-#include <ctype.h>
-
-#define SN_API_NOT_YET_FROZEN 1
-#include <libsn/sn-launcher.h>
 
 int min(int a, int b) {
     return (a < b ? a : b);
diff --git a/src/window.c b/src/window.c
index d84f8869..bee3fa66 100644
--- a/src/window.c
+++ b/src/window.c
@@ -9,6 +9,8 @@
  */
 #include "all.h"
 
+#include <math.h>
+
 /*
  * Frees an i3Window and all its members.
  *
diff --git a/src/x.c b/src/x.c
index 712cf89c..e89f5213 100644
--- a/src/x.c
+++ b/src/x.c
@@ -10,6 +10,8 @@
  */
 #include "all.h"
 
+#include <unistd.h>
+
 #ifndef MAX
 #define MAX(x, y) ((x) > (y) ? (x) : (y))
 #endif
diff --git a/src/xcursor.c b/src/xcursor.c
index cffb094b..cb98399f 100644
--- a/src/xcursor.c
+++ b/src/xcursor.c
@@ -9,13 +9,12 @@
  */
 #include <config.h>
 
+#include "all.h"
+
 #include <assert.h>
 #include <err.h>
-#include <xcb/xcb_cursor.h>
 
-#include "i3.h"
-#include "xcb.h"
-#include "xcursor.h"
+#include <xcb/xcb_cursor.h>
 
 static xcb_cursor_context_t *ctx;
 static xcb_cursor_t cursors[XCURSOR_CURSOR_MAX];
diff --git a/testcases/inject_randr1.5.c b/testcases/inject_randr1.5.c
index 819c029b..9c0b73d4 100644
--- a/testcases/inject_randr1.5.c
+++ b/testcases/inject_randr1.5.c
@@ -16,15 +16,17 @@
 
 #include <ev.h>
 #include <fcntl.h>
-#include <sys/types.h>
-#include <sys/socket.h>
-#include <sys/un.h>
-#include <sys/time.h>
-#include <sys/resource.h>
-#include <sys/mman.h>
-#include <sys/stat.h>
-#include <sys/wait.h>
+#include <getopt.h>
 #include <libgen.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/stat.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/un.h>
+#include <sys/wait.h>
+#include <unistd.h>
 
 static void uds_connection_cb(EV_P_ ev_io *w, int revents);
 static void read_client_setup_request_cb(EV_P_ ev_io *w, int revents);