diff --git a/Source/am_map.h b/Source/am_map.h
index a715dd88..4f67505f 100644
--- a/Source/am_map.h
+++ b/Source/am_map.h
@@ -30,6 +30,7 @@
 #define __AMMAP_H__
 
 #include "d_event.h"
+#include "m_fixed.h"
 
 // Used by ST StatusBar stuff.
 #define AM_MSGHEADER (('a'<<24)+('m'<<16))
diff --git a/Source/d_french.h b/Source/d_french.h
index 4d8a6459..ce96818e 100644
--- a/Source/d_french.h
+++ b/Source/d_french.h
@@ -277,7 +277,7 @@
 //
 //  F_Finale.C
 //
-#define E1TEXT  
+#define E1TEXT  \
   "APRES AVOIR VAINCU LES GROS MECHANTS\n"\
   "ET NETTOYE LA BASE LUNAIRE, VOUS AVEZ\n"\
   "GAGNE, NON? PAS VRAI? OU EST DONC VOTRE\n"\
diff --git a/Source/d_main.h b/Source/d_main.h
index 6e8f5297..d7ed23be 100644
--- a/Source/d_main.h
+++ b/Source/d_main.h
@@ -30,6 +30,7 @@
 #ifndef __D_MAIN__
 #define __D_MAIN__
 
+#include "doomdef.h"
 #include "d_event.h"
 
 extern char **wadfiles;       // killough 11/98
diff --git a/Source/doomstat.h b/Source/doomstat.h
index 630f2824..199c0795 100644
--- a/Source/doomstat.h
+++ b/Source/doomstat.h
@@ -303,9 +303,6 @@ extern thinker_t thinkercap;  // Both the head and tail of the thinker list
 
 //-----------------------------------------------------------------------------
 
-// v1.1-like pitched sounds
-extern int pitched_sounds, default_pitched_sounds;     // killough 2/21/98
-
 extern int allow_pushers;         // MT_PUSH Things    // phares 3/10/98
 extern int default_allow_pushers;
 
diff --git a/Source/g_game.h b/Source/g_game.h
index a4021c1c..70fcfc20 100644
--- a/Source/g_game.h
+++ b/Source/g_game.h
@@ -39,7 +39,6 @@
 
 boolean G_Responder(event_t *ev);
 boolean G_CheckDemoStatus(void);
-boolean G_CheckDemoStatus(void);
 void G_DeathMatchSpawnPlayer(int playernum);
 void G_InitNew(skill_t skill, int episode, int map);
 void G_DeferedInitNew(skill_t skill, int episode, int map);
@@ -63,13 +62,9 @@ void G_DoReborn(int playernum);
 byte *G_ReadOptions(byte *demo_p);         // killough 3/1/98
 byte *G_WriteOptions(byte *demo_p);        // killough 3/1/98
 void G_PlayerReborn(int player);
-void G_InitNew(skill_t skill, int episode, int map);
 void G_DoVictory(void);
 ULong64 G_Signature(void);      // killough 12/98
 
-// killough 1/18/98: Doom-style printf;   killough 4/25/98: add gcc attributes
-void dprintf(const char *, ...) __attribute__((format(printf,1,2)));
-
 // killough 5/2/98: moved from m_misc.c:
 
 extern int  key_right;
diff --git a/Source/m_cheat.h b/Source/m_cheat.h
index 51536e51..c24ea0c0 100644
--- a/Source/m_cheat.h
+++ b/Source/m_cheat.h
@@ -29,6 +29,8 @@
 #ifndef __M_CHEAT__
 #define __M_CHEAT__
 
+#include "doomtype.h"
+
 // killough 4/16/98: Cheat table structure
 
 extern struct cheat_s {
diff --git a/Source/m_misc.h b/Source/m_misc.h
index 4e305bca..9d9cd8be 100644
--- a/Source/m_misc.h
+++ b/Source/m_misc.h
@@ -30,6 +30,7 @@
 #define __M_MISC__
 
 #include "doomtype.h"
+#include "doomdef.h"
 
 //
 // MISC
diff --git a/Source/p_inter.h b/Source/p_inter.h
index 7350bc6c..13feb46c 100644
--- a/Source/p_inter.h
+++ b/Source/p_inter.h
@@ -59,11 +59,6 @@ extern int blue_armor_class;
 extern int max_soul;
 extern int soul_health;
 extern int mega_health;
-extern int god_health;
-extern int idfa_armor;
-extern int idfa_armor_class;
-extern int idkfa_armor;
-extern int idkfa_armor_class;
 extern int bfgcells;
 extern int maxammo[], clipammo[];
 
diff --git a/Source/p_pspr.h b/Source/p_pspr.h
index e496d14c..9be8c1aa 100644
--- a/Source/p_pspr.h
+++ b/Source/p_pspr.h
@@ -29,6 +29,8 @@
 #ifndef __P_PSPR__
 #define __P_PSPR__
 
+#include "doomdef.h"
+
 // Basic data types.
 // Needs fixed point, and BAM angles.
 
diff --git a/Source/p_saveg.h b/Source/p_saveg.h
index 23f28eb7..786858e2 100644
--- a/Source/p_saveg.h
+++ b/Source/p_saveg.h
@@ -29,6 +29,8 @@
 #ifndef __P_SAVEG__
 #define __P_SAVEG__
 
+#include "doomtype.h"
+
 // Persistent storage/archiving.
 // These are the load / save game routines.
 void P_ArchivePlayers(void);
diff --git a/Source/p_setup.h b/Source/p_setup.h
index 37ccbe78..20bf6f2e 100644
--- a/Source/p_setup.h
+++ b/Source/p_setup.h
@@ -29,6 +29,7 @@
 #ifndef __P_SETUP__
 #define __P_SETUP__
 
+#include "doomdef.h"
 #include "p_mobj.h"
 
 void P_SetupLevel(int episode, int map, int playermask, skill_t skill);
diff --git a/Source/p_spec.h b/Source/p_spec.h
index 30d78352..d45d38e5 100644
--- a/Source/p_spec.h
+++ b/Source/p_spec.h
@@ -864,8 +864,6 @@ void T_Friction(friction_t *);  // phares 3/12/98: friction thinker
 
 void T_Pusher(pusher_t *);      // phares 3/20/98: Push thinker
 
-void T_FireFlicker(fireflicker_t *);  // killough 10/4/98
-
 ////////////////////////////////////////////////////////////////
 //
 // Linedef and sector special handler prototypes
@@ -1003,8 +1001,6 @@ void P_RemoveAllActiveCeilings(void);                //jff 2/22/98
 
 void P_AddActiveCeiling(ceiling_t *c);
 
-void P_RemoveActiveCeiling(ceiling_t *c);
-
 int P_ActivateInStasisCeiling(line_t *line); 
 
 mobj_t *P_GetPushThing(int);                                // phares 3/23/98
diff --git a/Source/p_tick.h b/Source/p_tick.h
index 325fd26f..db037454 100644
--- a/Source/p_tick.h
+++ b/Source/p_tick.h
@@ -27,6 +27,7 @@
 #define __P_TICK__
 
 #include "d_think.h"
+#include "p_mobj.h"
 
 // Called by C_Ticker, can call G_PlayerExited.
 // Carries out all thinking of monsters and players.
diff --git a/Source/r_bsp.h b/Source/r_bsp.h
index 761698cc..16aa9ce8 100644
--- a/Source/r_bsp.h
+++ b/Source/r_bsp.h
@@ -29,6 +29,8 @@
 #ifndef __R_BSP__
 #define __R_BSP__
 
+#include "r_defs.h"
+
 extern seg_t    *curline;
 extern side_t   *sidedef;
 extern line_t   *linedef;
diff --git a/Source/r_draw.h b/Source/r_draw.h
index c8be4e20..281d9bb8 100644
--- a/Source/r_draw.h
+++ b/Source/r_draw.h
@@ -87,8 +87,6 @@ void R_FillBackScreen(void);
 // If the view size is not full screen, draws a border around it.
 void R_DrawViewBorder(void);
 
-void R_DrawTLColumn(void);    // drawing translucent textures     // phares
-
 extern byte *tranmap;         // translucency filter maps 256x256  // phares 
 extern byte *main_tranmap;    // killough 4/11/98
 extern byte *ylookup[];       // killough 11/98
diff --git a/Source/r_main.h b/Source/r_main.h
index 9274a335..b5f41adb 100644
--- a/Source/r_main.h
+++ b/Source/r_main.h
@@ -38,8 +38,6 @@
 
 extern fixed_t  viewcos;
 extern fixed_t  viewsin;
-extern int      viewwidth;
-extern int      viewheight;
 extern int      viewwindowx;
 extern int      viewwindowy;
 extern int      centerx;
@@ -69,9 +67,7 @@ extern int      loopcount;
 // killough 3/20/98: Allow colormaps to be dynamic (e.g. underwater)
 extern lighttable_t *(*scalelight)[MAXLIGHTSCALE];
 extern lighttable_t *(*zlight)[MAXLIGHTZ];
-extern lighttable_t *fullcolormap;
 extern int numcolormaps;    // killough 4/4/98: dynamic number of maps
-extern lighttable_t **colormaps;
 // killough 3/20/98, 4/4/98: end dynamic colormaps
 
 extern int          extralight;
diff --git a/Source/r_segs.h b/Source/r_segs.h
index 63adc94f..d72c0ddb 100644
--- a/Source/r_segs.h
+++ b/Source/r_segs.h
@@ -29,6 +29,8 @@
 #ifndef __R_SEGS__
 #define __R_SEGS__
 
+#include "r_defs.h"
+
 void R_RenderMaskedSegRange(drawseg_t *ds, int x1, int x2);
 void R_StoreWallRange(int start, int stop);
 
diff --git a/Source/r_things.h b/Source/r_things.h
index d092e397..bbf8bce2 100644
--- a/Source/r_things.h
+++ b/Source/r_things.h
@@ -29,6 +29,10 @@
 #ifndef __R_THINGS__
 #define __R_THINGS__
 
+#include "doomdef.h"
+#include "m_fixed.h"
+#include "r_defs.h"
+
 // Constant arrays used for psprite clipping and initializing clipping.
 
 extern short negonearray[MAX_SCREENWIDTH];         // killough 2/8/98:
diff --git a/Source/s_sound.h b/Source/s_sound.h
index ad9ab085..7aca180a 100644
--- a/Source/s_sound.h
+++ b/Source/s_sound.h
@@ -29,6 +29,8 @@
 #ifndef __S_SOUND__
 #define __S_SOUND__
 
+#include "p_mobj.h"
+
 //
 // Initializes sound stuff, including volume
 // Sets channels, SFX and music volume,
diff --git a/Source/st_stuff.h b/Source/st_stuff.h
index a04c889c..62e322ad 100644
--- a/Source/st_stuff.h
+++ b/Source/st_stuff.h
@@ -75,8 +75,6 @@ typedef enum
   GetChatState
 } st_chatstateenum_t;
 
-boolean ST_Responder(event_t* ev);
-
 // killough 5/2/98: moved from m_misc.c:
 
 extern int health_red;    // health amount less than which status is red
diff --git a/Source/wi_stuff.h b/Source/wi_stuff.h
index ffeca7bc..7c31a13b 100644
--- a/Source/wi_stuff.h
+++ b/Source/wi_stuff.h
@@ -32,6 +32,7 @@
 //#include "v_video.h"
 
 #include "doomdef.h"
+#include "d_player.h"
 
 // States for the intermission