diff --git a/setup/multiplayer.c b/setup/multiplayer.c
index b898b6f95..c856d3dec 100644
--- a/setup/multiplayer.c
+++ b/setup/multiplayer.c
@@ -16,6 +16,7 @@
 
 #include <stdint.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "d_iwad.h"
 #include "doomdef.h"
diff --git a/src/i_endoom.c b/src/i_endoom.c
index 0004501ad..7e0cba71c 100644
--- a/src/i_endoom.c
+++ b/src/i_endoom.c
@@ -15,6 +15,8 @@
 //    Exit text-mode ENDOOM screen.
 //
 
+#include <string.h>
+
 #include "doomtype.h"
 #include "i_printf.h"
 #include "i_video.h"
diff --git a/src/i_flickstick.c b/src/i_flickstick.c
index 0edbff85c..eb1becb69 100644
--- a/src/i_flickstick.c
+++ b/src/i_flickstick.c
@@ -25,10 +25,12 @@
 //
 //----------------------------------------------------------------------------
 
-#include "g_game.h"
+#include <math.h>
+#include <string.h>
+
 #include "i_flickstick.h"
+#include "doomstat.h"
 #include "i_gamepad.h"
-#include "i_input.h"
 #include "m_config.h"
 
 #define MAX_F 0.999999f
diff --git a/src/i_gamepad.c b/src/i_gamepad.c
index 1181efaa4..a8a104738 100644
--- a/src/i_gamepad.c
+++ b/src/i_gamepad.c
@@ -17,6 +17,7 @@
 #include "SDL.h"
 
 #include <math.h>
+#include <string.h>
 
 #include "g_game.h"
 #include "i_flickstick.h"
diff --git a/src/i_input.c b/src/i_input.c
index 18036e98a..8fdb1b58a 100644
--- a/src/i_input.c
+++ b/src/i_input.c
@@ -17,6 +17,8 @@
 
 #include "SDL.h"
 
+#include <string.h>
+
 #include "d_event.h"
 #include "d_main.h"
 #include "doomkeys.h"
diff --git a/src/i_pcsound.c b/src/i_pcsound.c
index f6ea2138e..bb747edb4 100644
--- a/src/i_pcsound.c
+++ b/src/i_pcsound.c
@@ -19,6 +19,8 @@
 #include "al.h"
 #include "alext.h"
 
+#include <string.h>
+
 #include "doomstat.h"
 #include "doomtype.h"
 #include "i_oalcommon.h"
diff --git a/src/i_rumble.c b/src/i_rumble.c
index 20ee49c11..30591c113 100644
--- a/src/i_rumble.c
+++ b/src/i_rumble.c
@@ -28,7 +28,6 @@
 #include "m_config.h"
 #include "p_mobj.h"
 #include "sounds.h"
-#include "w_wad.h"
 
 #define MAX_RUMBLE_COUNT 4
 #define MAX_RUMBLE_SDL   0xFFFF
diff --git a/src/i_video.c b/src/i_video.c
index bd87588a7..6cf951574 100644
--- a/src/i_video.c
+++ b/src/i_video.c
@@ -26,6 +26,7 @@
 #include "SDL.h"
 
 #include <limits.h>
+#include <math.h>
 #include <stdio.h>
 #include <stdlib.h>
 
diff --git a/src/mn_setup.c b/src/mn_setup.c
index 3702e7578..2628397bf 100644
--- a/src/mn_setup.c
+++ b/src/mn_setup.c
@@ -13,6 +13,9 @@
 //  GNU General Public License for more details.
 //
 
+#include <ctype.h>
+#include <math.h>
+#include <stdio.h>
 #include <string.h>
 
 #include "hu_command.h"
diff --git a/src/st_stuff.c b/src/st_stuff.c
index 82a343b53..de3d1bcc3 100644
--- a/src/st_stuff.c
+++ b/src/st_stuff.c
@@ -20,6 +20,7 @@
 //
 //-----------------------------------------------------------------------------
 
+#include <math.h>
 #include <stdlib.h>
 
 #include "am_map.h"
diff --git a/textscreen/txt_fileselect.c b/textscreen/txt_fileselect.c
index 858c2c178..1e0f080a2 100644
--- a/textscreen/txt_fileselect.c
+++ b/textscreen/txt_fileselect.c
@@ -15,6 +15,7 @@
 // Routines for selecting files.
 //
 
+#include <ctype.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>