diff --git a/Source/control.cpp b/Source/control.cpp
index a4945e628..65ce3a625 100644
--- a/Source/control.cpp
+++ b/Source/control.cpp
@@ -11,7 +11,7 @@ int chrbtn[4];
 BYTE *pMultiBtns;
 BYTE *pPanelButtons;
 BYTE *pChrPanel;
-int lvlbtndown;
+BOOL lvlbtndown;
 char sgszTalkSave[8][80];
 int dropGoldValue;
 BOOL drawmanaflag;
@@ -38,17 +38,17 @@ int sbooktab;
 int pSplType;
 int frame;
 int initialDropGoldIndex;
-int talkflag;
+BOOL talkflag;
 BYTE *pSBkIconCels;
-int sbookflag;
-int chrflag;
+BOOL sbookflag;
+BOOL chrflag;
 BOOL drawbtnflag;
 BYTE *pSpellBkCel;
 char infostr[MAX_PATH];
 int numpanbtns;
 BYTE *pStatusPanel;
 char panelstr[256];
-int panelflag;
+BOOL panelflag;
 BYTE SplTransTbl[256];
 int initialDropGoldValue;
 BYTE *pSpellCels;
@@ -1131,7 +1131,7 @@ void InitControlPan()
 	CelDecodeRect(pLifeBuff, 0, 87, 88, pStatusPanel, 1, 88);
 	CelDecodeRect(pManaBuff, 0, 87, 88, pStatusPanel, 2, 88);
 	MemFreeDbg(pStatusPanel);
-	talkflag = 0;
+	talkflag = FALSE;
 	if (gbMaxPlayers != 1) {
 		pTalkPanel = LoadFileInMem("CtrlPan\\TalkPanl.CEL", NULL);
 		CelDecodeRect(pBtmBuff, 0, (PANEL_HEIGHT + 16) * 2 - 1, PANEL_WIDTH, pTalkPanel, 1, PANEL_WIDTH);
@@ -1145,8 +1145,8 @@ void InitControlPan()
 		for (i = 0; i < sizeof(talkbtndown) / sizeof(talkbtndown[0]); i++)
 			talkbtndown[i] = FALSE;
 	}
-	panelflag = 0;
-	lvlbtndown = 0;
+	panelflag = FALSE;
+	lvlbtndown = FALSE;
 	pPanelButtons = LoadFileInMem("CtrlPan\\Panel8bu.CEL", NULL);
 	for (i = 0; i < sizeof(panbtn) / sizeof(panbtn[0]); i++)
 		panbtn[i] = 0;
@@ -1164,13 +1164,13 @@ void InitControlPan()
 	ClearPanel();
 	drawhpflag = TRUE;
 	drawmanaflag = TRUE;
-	chrflag = 0;
+	chrflag = FALSE;
 	spselflag = 0;
 	pSpellBkCel = LoadFileInMem("Data\\SpellBk.CEL", NULL);
 	pSBkBtnCel = LoadFileInMem("Data\\SpellBkB.CEL", NULL);
 	pSBkIconCels = LoadFileInMem("Data\\SpellI2.CEL", NULL);
 	sbooktab = 0;
-	sbookflag = 0;
+	sbookflag = FALSE;
 	if (plr[myplr]._pClass == PC_WARRIOR) {
 		SpellPages[0][0] = SPL_REPAIR;
 	} else if (plr[myplr]._pClass == PC_ROGUE) {
@@ -1323,7 +1323,7 @@ void CheckPanelInfo()
 {
 	int i, c, v, s;
 
-	panelflag = 0;
+	panelflag = FALSE;
 	ClearPanel();
 	for (i = 0; i < numpanbtns; i++) {
 		if (MouseX >= PanBtnPos[i][0]
@@ -1343,14 +1343,14 @@ void CheckPanelInfo()
 				AddPanelString(tempstr, TRUE);
 			}
 			infoclr = COL_WHITE;
-			panelflag = 1;
+			panelflag = TRUE;
 			pinfoflag = TRUE;
 		}
 	}
 	if (!spselflag && MouseX >= 565 && MouseX < 621 && MouseY >= 416 && MouseY < 472) {
 		strcpy(infostr, "Select current spell button");
 		infoclr = COL_WHITE;
-		panelflag = 1;
+		panelflag = TRUE;
 		pinfoflag = TRUE;
 		strcpy(tempstr, "Hotkey : 's'");
 		AddPanelString(tempstr, TRUE);
@@ -1439,10 +1439,10 @@ void CheckBtnUp()
 		switch (i) {
 		case PANBTN_CHARINFO:
 			questlog = FALSE;
-			chrflag = chrflag == 0;
+			chrflag = !chrflag;
 			break;
 		case PANBTN_QLOG:
-			chrflag = 0;
+			chrflag = FALSE;
 			if (!questlog)
 				StartQuestlog();
 			else
@@ -1457,7 +1457,7 @@ void CheckBtnUp()
 			gamemenuOff = 0;
 			break;
 		case PANBTN_INVENTORY:
-			sbookflag = 0;
+			sbookflag = FALSE;
 			invflag = invflag == 0;
 			if (dropGoldFlag) {
 				dropGoldFlag = FALSE;
@@ -1470,7 +1470,7 @@ void CheckBtnUp()
 				dropGoldFlag = FALSE;
 				dropGoldValue = 0;
 			}
-			sbookflag = sbookflag == 0;
+			sbookflag = !sbookflag;
 			break;
 		case PANBTN_SENDMSG:
 			if (talkflag)
@@ -1923,14 +1923,14 @@ void MY_PlrStringXY(int x, int y, int width, char *pszStr, char col, int base)
 void CheckLvlBtn()
 {
 	if (!lvlbtndown && MouseX >= 40 && MouseX <= 81 && MouseY >= 313 && MouseY <= 335)
-		lvlbtndown = 1;
+		lvlbtndown = TRUE;
 }
 
 void ReleaseLvlBtn()
 {
 	if (MouseX >= 40 && MouseX <= 81 && MouseY >= 313 && MouseY <= 335)
-		chrflag = 1;
-	lvlbtndown = 0;
+		chrflag = TRUE;
+	lvlbtndown = FALSE;
 }
 
 void DrawLevelUpIcon()
@@ -2549,7 +2549,7 @@ void control_type_message()
 		return;
 	}
 
-	talkflag = 1;
+	talkflag = TRUE;
 	sgszTalkMsg[0] = 0;
 	frame = 1;
 	for (i = 0; i < 3; i++) {
@@ -2562,7 +2562,7 @@ void control_type_message()
 
 void control_reset_talk()
 {
-	talkflag = 0;
+	talkflag = FALSE;
 	sgbPlrTalkTbl = 0;
 	drawpanflag = 255;
 }
diff --git a/Source/control.h b/Source/control.h
index 9435477a9..803bdc4c3 100644
--- a/Source/control.h
+++ b/Source/control.h
@@ -11,7 +11,7 @@ extern int chrbtn[4];
 extern BYTE *pMultiBtns;
 extern BYTE *pPanelButtons;
 extern BYTE *pChrPanel;
-extern int lvlbtndown;
+extern BOOL lvlbtndown;
 extern int dropGoldValue;
 extern BOOL drawmanaflag;
 extern BOOL chrbtnactive;
@@ -35,17 +35,17 @@ extern int sbooktab;
 extern int pSplType;
 extern int frame;
 extern int initialDropGoldIndex;
-extern int talkflag;
+extern BOOL talkflag;
 extern BYTE *pSBkIconCels;
-extern int sbookflag;
-extern int chrflag;
+extern BOOL sbookflag;
+extern BOOL chrflag;
 extern BOOL drawbtnflag;
 extern BYTE *pSpellBkCel;
 extern char infostr[MAX_PATH];
 extern int numpanbtns;
 extern BYTE *pStatusPanel;
 extern char panelstr[256];
-extern int panelflag;
+extern BOOL panelflag;
 extern BYTE SplTransTbl[256];
 extern int initialDropGoldValue;
 extern BYTE *pSpellCels;
diff --git a/Source/cursor.cpp b/Source/cursor.cpp
index b35315ed3..d04284aac 100644
--- a/Source/cursor.cpp
+++ b/Source/cursor.cpp
@@ -259,8 +259,8 @@ void CheckCursMove()
 	}
 	pcursinvitem = -1;
 	pcursplr = -1;
-	uitemflag = 0;
-	panelflag = 0;
+	uitemflag = FALSE;
+	panelflag = FALSE;
 	trigflag = FALSE;
 
 	if (plr[myplr]._pInvincible) {
diff --git a/Source/diablo.cpp b/Source/diablo.cpp
index 50e58a4c0..e43936324 100644
--- a/Source/diablo.cpp
+++ b/Source/diablo.cpp
@@ -19,14 +19,14 @@ int glEndSeed[NUMLEVELS];
 BOOL gbLoadGame;
 HINSTANCE ghInst;
 int DebugMonsters[10];
-char cineflag;
+BOOLEAN cineflag;
 int drawpanflag;
-int visiondebug;
-int scrollflag; /* unused */
+BOOL visiondebug;
+BOOL scrollflag; /* unused */
 BOOL light4flag;
-int leveldebug;
-int monstdebug;
-int trigdebug; /* unused */
+BOOL leveldebug;
+BOOL monstdebug;
+BOOL trigdebug; /* unused */
 int setseed;
 int debugmonsttypes;
 int PauseMode;
@@ -370,7 +370,7 @@ void diablo_parse_flags(char *args)
 				break;
 			case 'l':
 				setlevel = FALSE;
-				leveldebug = 1;
+				leveldebug = TRUE;
 				while (isspace(*args)) {
 					args++;
 				}
@@ -392,7 +392,7 @@ void diablo_parse_flags(char *args)
 				plr[0].plrlevel = i;
 				break;
 			case 'm':
-				monstdebug = 1;
+				monstdebug = TRUE;
 				while (isspace(*args)) {
 					args++;
 				}
@@ -432,7 +432,7 @@ void diablo_parse_flags(char *args)
 				debug_mode_key_s = 1;
 				break;
 			case 't':
-				leveldebug = 1;
+				leveldebug = TRUE;
 				setlevel = TRUE;
 				while (isspace(*args)) {
 					args++;
@@ -445,7 +445,7 @@ void diablo_parse_flags(char *args)
 				setlvlnum = i;
 				break;
 			case 'v':
-				visiondebug = 1;
+				visiondebug = TRUE;
 				break;
 			case 'w':
 				debug_mode_key_w = 1;
@@ -1066,11 +1066,11 @@ void PressKey(int vkey)
 			track_repeat_walk(0);
 		} else {
 			invflag = 0;
-			chrflag = 0;
-			sbookflag = 0;
+			chrflag = FALSE;
+			sbookflag = FALSE;
 			spselflag = 0;
 			if (qtextflag && leveltype == DTYPE_TOWN) {
-				qtextflag = 0;
+				qtextflag = FALSE;
 				sfx_stop();
 			}
 			questlog = FALSE;
@@ -1184,11 +1184,11 @@ void PressKey(int vkey)
 		}
 		helpflag = 0;
 		invflag = 0;
-		chrflag = 0;
-		sbookflag = 0;
+		chrflag = FALSE;
+		sbookflag = FALSE;
 		spselflag = 0;
 		if (qtextflag && leveltype == DTYPE_TOWN) {
-			qtextflag = 0;
+			qtextflag = FALSE;
 			sfx_stop();
 		}
 		questlog = FALSE;
@@ -1247,7 +1247,7 @@ void PressChar(int vkey)
 	case 'I':
 	case 'i':
 		if (!stextflag) {
-			sbookflag = 0;
+			sbookflag = FALSE;
 			invflag = invflag == 0;
 			if (!invflag || chrflag) {
 				if (MouseX < 480 && MouseY < PANEL_TOP) {
@@ -1264,7 +1264,7 @@ void PressChar(int vkey)
 	case 'c':
 		if (!stextflag) {
 			questlog = FALSE;
-			chrflag = chrflag == 0;
+			chrflag = !chrflag;
 			if (!chrflag || invflag) {
 				if (MouseX > 160 && MouseY < PANEL_TOP) {
 					SetCursorPos(MouseX - 160, MouseY);
@@ -1279,7 +1279,7 @@ void PressChar(int vkey)
 	case 'Q':
 	case 'q':
 		if (!stextflag) {
-			chrflag = 0;
+			chrflag = FALSE;
 			if (!questlog) {
 				StartQuestlog();
 			} else {
@@ -1307,7 +1307,7 @@ void PressChar(int vkey)
 	case 'b':
 		if (!stextflag) {
 			invflag = 0;
-			sbookflag = sbookflag == 0;
+			sbookflag = !sbookflag;
 		}
 		return;
 	case '+':
diff --git a/Source/diablo.h b/Source/diablo.h
index d39131414..312a2d240 100644
--- a/Source/diablo.h
+++ b/Source/diablo.h
@@ -100,14 +100,14 @@ extern int glEndSeed[NUMLEVELS];
 extern BOOL gbLoadGame;
 extern HINSTANCE ghInst;
 extern int DebugMonsters[10];
-extern char cineflag;
+extern BOOLEAN cineflag;
 extern int drawpanflag;
-extern int visiondebug;
-extern int scrollflag; /* unused */
+extern BOOL visiondebug;
+extern BOOL scrollflag; /* unused */
 extern BOOL light4flag;
-extern int leveldebug;
-extern int monstdebug;
-extern int trigdebug; /* unused */
+extern BOOL leveldebug;
+extern BOOL monstdebug;
+extern BOOL trigdebug; /* unused */
 extern int setseed;
 extern int debugmonsttypes;
 extern int PauseMode;
diff --git a/Source/gendung.cpp b/Source/gendung.cpp
index d785186ed..c63bdf3cb 100644
--- a/Source/gendung.cpp
+++ b/Source/gendung.cpp
@@ -2,7 +2,7 @@
 
 WORD level_frame_types[MAXTILES];
 int themeCount;
-char nTransTable[2049];
+BOOLEAN nTransTable[2049];
 //int dword_52D204;
 int dMonster[MAXDUNX][MAXDUNY];
 BYTE dungeon[DMAXX][DMAXY];
@@ -29,7 +29,7 @@ char dTransVal[MAXDUNX][MAXDUNY];
 BOOLEAN nTrapTable[2049];
 BYTE leveltype;
 BYTE currlevel;
-char TransList[256];
+BOOLEAN TransList[256];
 BOOLEAN nSolidTable[2049];
 int level_frame_count[MAXTILES];
 ScrollStruct ScrollInfo;
@@ -42,13 +42,13 @@ int dword_5C2FFC;
 int scr_pix_width;
 int scr_pix_height;
 char dArch[MAXDUNX][MAXDUNY];
-char nBlockTable[2049];
+BOOLEAN nBlockTable[2049];
 BYTE *pSpecialCels;
 char dFlags[MAXDUNX][MAXDUNY];
 char dItem[MAXDUNX][MAXDUNY];
 BYTE setlvlnum;
 int level_frame_sizes[MAXTILES];
-char nMissileTable[2049];
+BOOLEAN nMissileTable[2049];
 char *pSetPiece_2;
 char setlvltype;
 BOOLEAN setlevel;
@@ -107,11 +107,11 @@ void FillSolidBlockTbls()
 		if (bv & 1)
 			nSolidTable[i] = 1;
 		if (bv & 2)
-			nBlockTable[i] = 1;
+			nBlockTable[i] = TRUE;
 		if (bv & 4)
-			nMissileTable[i] = 1;
+			nMissileTable[i] = TRUE;
 		if (bv & 8)
-			nTransTable[i] = 1;
+			nTransTable[i] = TRUE;
 		if (bv & 0x80)
 			nTrapTable[i] = 1;
 		block_lvid[i] = (bv & 0x70) >> 4; /* beta: (bv >> 4) & 7 */
diff --git a/Source/gendung.h b/Source/gendung.h
index 8c495337e..344a9e916 100644
--- a/Source/gendung.h
+++ b/Source/gendung.h
@@ -4,7 +4,7 @@
 
 extern WORD level_frame_types[MAXTILES];
 extern int themeCount;
-extern char nTransTable[2049];
+extern BOOLEAN nTransTable[2049];
 //int dword_52D204;
 extern int dMonster[MAXDUNX][MAXDUNY];
 extern BYTE dungeon[DMAXX][DMAXY];
@@ -31,7 +31,7 @@ extern char dTransVal[MAXDUNX][MAXDUNY];
 extern BOOLEAN nTrapTable[2049];
 extern BYTE leveltype;
 extern BYTE currlevel;
-extern char TransList[256];
+extern BOOLEAN TransList[256];
 extern BOOLEAN nSolidTable[2049];
 extern int level_frame_count[MAXTILES];
 extern ScrollStruct ScrollInfo;
@@ -44,13 +44,13 @@ extern int dword_5C2FFC;
 extern int scr_pix_width;
 extern int scr_pix_height;
 extern char dArch[MAXDUNX][MAXDUNY];
-extern char nBlockTable[2049];
+extern BOOLEAN nBlockTable[2049];
 extern BYTE *pSpecialCels;
 extern char dFlags[MAXDUNX][MAXDUNY];
 extern char dItem[MAXDUNX][MAXDUNY];
 extern BYTE setlvlnum;
 extern int level_frame_sizes[MAXTILES];
-extern char nMissileTable[2049];
+extern BOOLEAN nMissileTable[2049];
 extern char *pSetPiece_2;
 extern char setlvltype;
 extern BOOLEAN setlevel;
diff --git a/Source/items.cpp b/Source/items.cpp
index 3ab8b9f1b..e05d89a80 100644
--- a/Source/items.cpp
+++ b/Source/items.cpp
@@ -1,7 +1,7 @@
 #include "diablo.h"
 
 int itemactive[MAXITEMS];
-int uitemflag;
+BOOL uitemflag;
 int itemavail[MAXITEMS];
 ItemStruct curruitem;
 ItemGetRecordStruct itemrecord[MAXITEMS];
@@ -282,7 +282,7 @@ void InitItems()
 			AddInitItems();
 	}
 
-	uitemflag = 0;
+	uitemflag = FALSE;
 }
 
 void CalcPlrItemVals(int p, BOOL Loadgfx)
@@ -3054,7 +3054,7 @@ void PrintItemDetails(ItemStruct *x)
 	}
 	if (x->_iMagical == ITEM_QUALITY_UNIQUE) {
 		AddPanelString("unique item", TRUE);
-		uitemflag = 1;
+		uitemflag = TRUE;
 		curruitem = *x;
 	}
 	PrintItemMisc(x);
diff --git a/Source/items.h b/Source/items.h
index 90ac1b8c8..4e8d068c1 100644
--- a/Source/items.h
+++ b/Source/items.h
@@ -3,7 +3,7 @@
 #define __ITEMS_H__
 
 extern int itemactive[MAXITEMS];
-extern int uitemflag;
+extern BOOL uitemflag;
 extern int itemavail[MAXITEMS];
 extern ItemStruct curruitem;
 extern ItemGetRecordStruct itemrecord[MAXITEMS];
diff --git a/Source/lighting.cpp b/Source/lighting.cpp
index c6a78f33a..632220a13 100644
--- a/Source/lighting.cpp
+++ b/Source/lighting.cpp
@@ -663,7 +663,8 @@ void DoUnVision(int nXPos, int nYPos, int nRadius)
 
 void DoVision(int nXPos, int nYPos, int nRadius, BOOL doautomap, BOOL visible)
 {
-	int nCrawlX, nCrawlY, nLineLen, nBlockerFlag, nTrans;
+	BOOL nBlockerFlag;
+	int nCrawlX, nCrawlY, nLineLen, nTrans;
 	int j, k, v, x1adj, x2adj, y1adj, y2adj;
 
 	if (nXPos >= 0 && nXPos <= MAXDUNX && nYPos >= 0 && nYPos <= MAXDUNY) {
@@ -723,7 +724,7 @@ void DoVision(int nXPos, int nYPos, int nRadius, BOOL doautomap, BOOL visible)
 					break;
 				}
 				if (nCrawlX >= 0 && nCrawlX <= MAXDUNX && nCrawlY >= 0 && nCrawlY <= MAXDUNY) {
-					nBlockerFlag = (BYTE)nBlockTable[dPiece[nCrawlX][nCrawlY]];
+					nBlockerFlag = nBlockTable[dPiece[nCrawlX][nCrawlY]];
 					if (!nBlockTable[dPiece[x1adj + nCrawlX][y1adj + nCrawlY]]
 					    || !nBlockTable[dPiece[x2adj + nCrawlX][y2adj + nCrawlY]]) {
 						if (doautomap) {
@@ -739,7 +740,7 @@ void DoVision(int nXPos, int nYPos, int nRadius, BOOL doautomap, BOOL visible)
 						if (!nBlockerFlag) {
 							nTrans = dTransVal[nCrawlX][nCrawlY];
 							if (nTrans != 0) {
-								TransList[nTrans] = 1;
+								TransList[nTrans] = TRUE;
 							}
 						}
 					}
@@ -1150,7 +1151,7 @@ void InitVision()
 	visionid = 1;
 
 	for (i = 0; i < TransVal; i++) {
-		TransList[i] = 0;
+		TransList[i] = FALSE;
 	}
 }
 
@@ -1223,7 +1224,7 @@ void ProcessVisionList()
 			}
 		}
 		for (i = 0; i < TransVal; i++) {
-			TransList[i] = 0;
+			TransList[i] = FALSE;
 		}
 		for (i = 0; i < numvision; i++) {
 			if (!VisionList[i]._ldel) {
diff --git a/Source/minitext.cpp b/Source/minitext.cpp
index 1e6798864..9d0eb0a3c 100644
--- a/Source/minitext.cpp
+++ b/Source/minitext.cpp
@@ -3,7 +3,7 @@
 int qtexty;
 char *qtextptr;
 int qtextSpd;
-char qtextflag;
+BOOLEAN qtextflag;
 int scrolltexty;
 int sgLastScroll;
 BYTE *pMedTextCels;
@@ -273,7 +273,7 @@ void DrawQText()
 			qtexty += 38;
 			qtextptr = pnl;
 			if (*pnl == '|') {
-				qtextflag = 0;
+				qtextflag = FALSE;
 			}
 			break;
 		}
diff --git a/Source/minitext.h b/Source/minitext.h
index d1250e7d3..3be2aeea6 100644
--- a/Source/minitext.h
+++ b/Source/minitext.h
@@ -5,7 +5,7 @@
 extern int qtexty;
 extern char *qtextptr;
 extern int qtextSpd;
-extern char qtextflag;
+extern BOOLEAN qtextflag;
 extern int scrolltexty;
 extern BYTE *pMedTextCels;
 extern BYTE *pTextBoxCels;
diff --git a/Source/missiles.cpp b/Source/missiles.cpp
index 940ac3077..27b8d8c73 100644
--- a/Source/missiles.cpp
+++ b/Source/missiles.cpp
@@ -4,9 +4,9 @@ int missileactive[MAXMISSILES];
 int missileavail[MAXMISSILES];
 MissileStruct missile[MAXMISSILES];
 int nummissiles;
-int ManashieldFlag;
+BOOL ManashieldFlag;
 ChainStruct chain[MAXMISSILES];
-int MissilePreFlag;
+BOOL MissilePreFlag;
 int numchains;
 
 int XDirAdd[8] = { 1, 0, -1, -1, -1, 0, 1, 1 };
@@ -390,7 +390,7 @@ void PutMissile(int i)
 		else
 			dMissile[x][y] = -1;
 		if (missile[i]._miPreFlag)
-			MissilePreFlag = 1;
+			MissilePreFlag = TRUE;
 	}
 }
 
@@ -1571,7 +1571,7 @@ void AddTown(int mi, int sx, int sy, int dx, int dy, int midir, char mienemy, in
 				tx = dx + CrawlTable[k - 1];
 				ty = dy + CrawlTable[k];
 				if (tx > 0 && tx < MAXDUNX && ty > 0 && ty < MAXDUNY) {
-					if (!(dObject[tx][ty] | dPlayer[tx][ty] | dMissile[tx][ty] | nSolidTable[dPiece[tx][ty]] | (BYTE)nMissileTable[dPiece[tx][ty]])) {
+					if (!(dObject[tx][ty] | dPlayer[tx][ty] | dMissile[tx][ty] | nSolidTable[dPiece[tx][ty]] | nMissileTable[dPiece[tx][ty]])) {
 						if (!CheckIfTrig(tx, ty)) {
 							missile[mi]._miDelFlag = FALSE;
 							missile[mi]._mix = tx;
@@ -1703,7 +1703,7 @@ void AddGuardian(int mi, int sx, int sy, int dx, int dy, int midir, char mienemy
 			pn = dPiece[tx][ty];
 			if (tx > 0 && tx < MAXDUNX && ty > 0 && ty < MAXDUNY) {
 				if (LineClear(sx, sy, tx, ty)) {
-					if (!(dMonster[tx][ty] | dObject[tx][ty] | dMissile[tx][ty] | nSolidTable[pn] | (BYTE)nMissileTable[pn])) {
+					if (!(dMonster[tx][ty] | dObject[tx][ty] | dMissile[tx][ty] | nSolidTable[pn] | nMissileTable[pn])) {
 						missile[mi]._miDelFlag = FALSE;
 						missile[mi]._mix = tx;
 						missile[mi]._miy = ty;
@@ -2093,7 +2093,7 @@ void AddIdentify(int mi, int sx, int sy, int dx, int dy, int midir, char mienemy
 	UseMana(id, SPL_IDENTIFY);
 	if (id == myplr) {
 		if (sbookflag)
-			sbookflag = 0;
+			sbookflag = FALSE;
 		if (!invflag)
 			invflag = 1;
 		SetCursor_(CURSOR_IDENTIFY);
@@ -2189,7 +2189,7 @@ void AddRepair(int mi, int sx, int sy, int dx, int dy, int midir, char mienemy,
 	UseMana(id, SPL_REPAIR);
 	if (id == myplr) {
 		if (sbookflag)
-			sbookflag = 0;
+			sbookflag = FALSE;
 		if (!invflag)
 			invflag = 1;
 		SetCursor_(CURSOR_REPAIR);
@@ -2202,7 +2202,7 @@ void AddRecharge(int mi, int sx, int sy, int dx, int dy, int midir, char mienemy
 	UseMana(id, SPL_RECHARGE);
 	if (id == myplr) {
 		if (sbookflag)
-			sbookflag = 0;
+			sbookflag = FALSE;
 		if (!invflag)
 			invflag = 1;
 		SetCursor_(CURSOR_RECHARGE);
@@ -2539,7 +2539,7 @@ void MI_Golem(int i)
 
 void MI_SetManashield(int i)
 {
-	ManashieldFlag = 1;
+	ManashieldFlag = TRUE;
 }
 
 void MI_LArrow(int i)
@@ -2930,13 +2930,13 @@ void MI_Lightctrl(int i)
 	/// ASSERT: assert((DWORD)pn <= MAXTILES);
 
 	if (missile[i]._misource == -1) {
-		if ((mx != missile[i]._misx || my != missile[i]._misy) && nMissileTable[pn] != 0) {
+		if ((mx != missile[i]._misx || my != missile[i]._misy) && nMissileTable[pn]) {
 			missile[i]._mirange = 0;
 		}
-	} else if (nMissileTable[pn] != 0) {
+	} else if (nMissileTable[pn]) {
 		missile[i]._mirange = 0;
 	}
-	if (nMissileTable[pn] == 0) {
+	if (!nMissileTable[pn]) {
 		if ((mx != missile[i]._miVar1 || my != missile[i]._miVar2) && mx > 0 && my > 0 && mx < MAXDUNX && my < MAXDUNY) {
 			if (missile[i]._misource != -1) {
 				if (missile[i]._micaster == 1
@@ -3665,7 +3665,7 @@ void MI_Wave(int i)
 	nya = sy + YDirAdd[sd];
 	pn = dPiece[nxa][nya];
 	/// ASSERT: assert((DWORD)pn <= MAXTILES);
-	if (nMissileTable[pn] == 0) {
+	if (!nMissileTable[pn]) {
 		AddMissile(nxa, nya, nxa + XDirAdd[sd], nya + YDirAdd[sd], plr[id]._pdir, MIS_FIREMOVE, 0, id, 0, missile[i]._mispllvl);
 		nxa += XDirAdd[dira];
 		nya += YDirAdd[dira];
@@ -4039,8 +4039,8 @@ void ProcessMissiles()
 		}
 	}
 
-	MissilePreFlag = 0;
-	ManashieldFlag = 0;
+	MissilePreFlag = FALSE;
+	ManashieldFlag = FALSE;
 
 	for (i = 0; i < nummissiles; i++) {
 		mi = missileactive[i];
diff --git a/Source/missiles.h b/Source/missiles.h
index 466bae271..b7e502c2c 100644
--- a/Source/missiles.h
+++ b/Source/missiles.h
@@ -6,9 +6,9 @@ extern int missileactive[MAXMISSILES];
 extern int missileavail[MAXMISSILES];
 extern MissileStruct missile[MAXMISSILES];
 extern int nummissiles;
-extern int ManashieldFlag;
+extern BOOL ManashieldFlag;
 extern ChainStruct chain[MAXMISSILES];
-extern int MissilePreFlag;
+extern BOOL MissilePreFlag;
 extern int numchains;
 
 void GetDamageAmt(int i, int *mind, int *maxd);
diff --git a/Source/player.cpp b/Source/player.cpp
index e9243f6ea..bdf53e39f 100644
--- a/Source/player.cpp
+++ b/Source/player.cpp
@@ -1017,7 +1017,7 @@ void PlrClrTrans(int x, int y)
 
 	for (i = y - 1; i <= y + 1; i++) {
 		for (j = x - 1; j <= x + 1; j++) {
-			TransList[dTransVal[j][i]] = 0;
+			TransList[dTransVal[j][i]] = FALSE;
 		}
 	}
 }
@@ -1027,12 +1027,12 @@ void PlrDoTrans(int x, int y)
 	int i, j;
 
 	if (leveltype != DTYPE_CATHEDRAL && leveltype != DTYPE_CATACOMBS) {
-		TransList[1] = 1;
+		TransList[1] = TRUE;
 	} else {
 		for (i = y - 1; i <= y + 1; i++) {
 			for (j = x - 1; j <= x + 1; j++) {
 				if (!nSolidTable[dPiece[j][i]] && dTransVal[j][i]) {
-					TransList[dTransVal[j][i]] = 1;
+					TransList[dTransVal[j][i]] = TRUE;
 				}
 			}
 		}
diff --git a/Source/scrollrt.cpp b/Source/scrollrt.cpp
index 63e6a32f9..c14672771 100644
--- a/Source/scrollrt.cpp
+++ b/Source/scrollrt.cpp
@@ -887,7 +887,7 @@ void scrollrt_draw_clipped_dungeon(BYTE *pBuff, int sx, int sy, int dx, int dy,
 		}
 	}
 	if (bArch != 0) {
-		cel_transparency_active = (BYTE)TransList[bMap];
+		cel_transparency_active = TransList[bMap];
 		Cel2DecodeLightTrans(pBuff, pSpecialCels, bArch, 64, 0, 8);
 	}
 }
@@ -1353,7 +1353,7 @@ void scrollrt_draw_clipped_dungeon_2(BYTE *pBuff, int sx, int sy, int skipChunks
 		}
 	}
 	if (bArch != 0) {
-		cel_transparency_active = (BYTE)TransList[bMap];
+		cel_transparency_active = TransList[bMap];
 		Cel2DecodeLightTrans(pBuff, pSpecialCels, bArch, 64, CelSkip, 8);
 	}
 }
@@ -1773,7 +1773,7 @@ void scrollrt_draw_dungeon(BYTE *pBuff, int sx, int sy, int capChunks, int CelCa
 		}
 	}
 	if (bArch != 0) {
-		cel_transparency_active = (BYTE)TransList[bMap];
+		cel_transparency_active = TransList[bMap];
 		CelDecodeHdrLightTrans(pBuff, pSpecialCels, bArch, 64, 0, CelCap);
 	}
 }
diff --git a/Source/stores.cpp b/Source/stores.cpp
index 604894195..948f64ccd 100644
--- a/Source/stores.cpp
+++ b/Source/stores.cpp
@@ -1432,9 +1432,9 @@ void StartStore(char s)
 	int i;
 
 	for (t = s;; t = STORE_SMITH) {
-		sbookflag = 0;
+		sbookflag = FALSE;
 		invflag = 0;
-		chrflag = 0;
+		chrflag = FALSE;
 		questlog = FALSE;
 		dropGoldFlag = FALSE;
 		ClearSText(0, 24);
diff --git a/Source/towners.cpp b/Source/towners.cpp
index 7b073fdf0..cb181498d 100644
--- a/Source/towners.cpp
+++ b/Source/towners.cpp
@@ -1,11 +1,11 @@
 #include "diablo.h"
 
-int storeflag;
+BOOL storeflag;
 int sgnCowMsg;
 int numtowners;
 DWORD sgdwCowClicks;
-int bannerflag; // unused 0x6AAC28
-int boyloadflag;
+BOOL bannerflag; // unused 0x6AAC28
+BOOL boyloadflag;
 BYTE *pCowCels;
 TownerStruct towner[16];
 
@@ -210,7 +210,7 @@ void InitBarOwner()
 {
 	int i;
 
-	bannerflag = 0; // unused
+	bannerflag = FALSE; // unused
 	InitTownerInfo(numtowners, 96, 1, TOWN_TAVERN, 55, 62, 3, 10);
 	InitQstSnds(numtowners);
 	towner[numtowners]._tNData = LoadFileInMem("Towners\\TwnF\\TwnFN.CEL", NULL);
@@ -275,7 +275,7 @@ void InitBoy()
 {
 	int i;
 
-	boyloadflag = 1;
+	boyloadflag = TRUE;
 	InitTownerInfo(numtowners, 96, 1, TOWN_PEGBOY, 11, 53, -1, 10);
 	InitQstSnds(numtowners);
 	towner[numtowners]._tNData = LoadFileInMem("Towners\\TownBoy\\PegKid1.CEL", NULL);
@@ -373,7 +373,7 @@ void InitCows()
 void InitTowners()
 {
 	numtowners = 0;
-	boyloadflag = 0;
+	boyloadflag = FALSE;
 	InitSmith();
 	InitHealer();
 	if (quests[QTYPE_BUTCH]._qactive && quests[QTYPE_BUTCH]._qactive != 3)
@@ -585,7 +585,7 @@ void TownerTalk(int first, int t)
 {
 	sgdwCowClicks = 0;
 	sgnCowMsg = 0;
-	storeflag = 1;
+	storeflag = TRUE;
 	InitQTextMsg(first);
 }