ANALYSIS: Add static casts to is* functions

This fixes a potential problem with passing char values that would be sign-extended and yield unexpected results.
See http://msdn.microsoft.com/en-us/library/ms245348.aspx

28 files changed, 53 insertions, 53 deletions

diff --git a/base/commandLine.cpp b/base/commandLine.cpp
index 6cb858525e..2620d69ba2 100644
--- a/base/commandLine.cpp
+++ b/base/commandLine.cpp
@@ -279,7 +279,7 @@ void registerDefaults() {
 // resp. between "--some-option" and "--no-some-option".
 #define DO_OPTION_BOOL(shortCmd, longCmd) \
 	if (isLongCmd ? (!strcmp(s+2, longCmd) || !strcmp(s+2, "no-"longCmd)) : (tolower(s[1]) == shortCmd)) { \
-		bool boolValue = (islower(s[1]) != 0); \
+		bool boolValue = (islower(static_cast<unsigned char>(s[1])) != 0); \
 		s += 2; \
 		if (isLongCmd) { \
 			boolValue = !strcmp(s, longCmd); \
diff --git a/common/config-file.cpp b/common/config-file.cpp
index 55941131ac..ea3feff8ae 100644
--- a/common/config-file.cpp
+++ b/common/config-file.cpp
@@ -38,7 +38,7 @@ namespace Common {
  */
 bool ConfigFile::isValidName(const Common::String &name) {
 	const char *p = name.c_str();
-	while (*p && (isalnum(*p) || *p == '-' || *p == '_' || *p == '.'))
+	while (*p && (isalnum(static_cast<unsigned char>(*p)) || *p == '-' || *p == '_' || *p == '.'))
 		p++;
 	return *p == 0;
 }
@@ -116,7 +116,7 @@ bool ConfigFile::loadFromStream(SeekableReadStream &stream) {
 			// is, verify that it only consists of alphanumerics,
 			// periods, dashes and underscores). Mohawk Living Books games
 			// can have periods in their section names.
-			while (*p && (isalnum(*p) || *p == '-' || *p == '_' || *p == '.'))
+			while (*p && (isalnum(static_cast<unsigned char>(*p)) || *p == '-' || *p == '_' || *p == '.'))
 				p++;
 
 			if (*p == '\0')
@@ -139,7 +139,7 @@ bool ConfigFile::loadFromStream(SeekableReadStream &stream) {
 
 			// Skip leading whitespaces
 			const char *t = line.c_str();
-			while (isspace(*t))
+			while (isspace(static_cast<unsigned char>(*t)))
 				t++;
 
 			// Skip empty lines / lines with only whitespace
diff --git a/common/config-manager.cpp b/common/config-manager.cpp
index 3941e27cc1..a9d8c89035 100644
--- a/common/config-manager.cpp
+++ b/common/config-manager.cpp
@@ -31,7 +31,7 @@ DECLARE_SINGLETON(Common::ConfigManager);
 
 static bool isValidDomainName(const Common::String &domName) {
 	const char *p = domName.c_str();
-	while (*p && (isalnum(*p) || *p == '-' || *p == '_'))
+	while (*p && (isalnum(static_cast<unsigned char>(*p)) || *p == '-' || *p == '_'))
 		p++;
 	return *p == 0;
 }
@@ -187,7 +187,7 @@ void ConfigManager::loadFromStream(SeekableReadStream &stream) {
 			// Get the domain name, and check whether it's valid (that
 			// is, verify that it only consists of alphanumerics,
 			// dashes and underscores).
-			while (*p && (isalnum(*p) || *p == '-' || *p == '_'))
+			while (*p && (isalnum(static_cast<unsigned char>(*p)) || *p == '-' || *p == '_'))
 				p++;
 
 			if (*p == '\0')
@@ -205,7 +205,7 @@ void ConfigManager::loadFromStream(SeekableReadStream &stream) {
 
 			// Skip leading whitespaces
 			const char *t = line.c_str();
-			while (isspace(*t))
+			while (isspace(static_cast<unsigned char>(*t)))
 				t++;
 
 			// Skip empty lines / lines with only whitespace
diff --git a/common/str.cpp b/common/str.cpp
index a2cd4a0193..32f4b44e79 100644
--- a/common/str.cpp
+++ b/common/str.cpp
@@ -405,7 +405,7 @@ void String::trim() {
 	makeUnique();
 
 	// Trim trailing whitespace
-	while (_size >= 1 && isspace(_str[_size - 1]))
+	while (_size >= 1 && isspace(static_cast<unsigned char>(_str[_size - 1])))
 		--_size;
 	_str[_size] = 0;
 
@@ -606,14 +606,14 @@ String operator+(const String &x, char y) {
 }
 
 char *ltrim(char *t) {
-	while (isspace(*t))
+	while (isspace(static_cast<unsigned char>(*t)))
 		t++;
 	return t;
 }
 
 char *rtrim(char *t) {
 	int l = strlen(t) - 1;
-	while (l >= 0 && isspace(t[l]))
+	while (l >= 0 && isspace(static_cast<unsigned char>(t[l])))
 		t[l--] = 0;
 	return t;
 }
diff --git a/common/xmlparser.cpp b/common/xmlparser.cpp
index 5217c4e82c..623619914a 100644
--- a/common/xmlparser.cpp
+++ b/common/xmlparser.cpp
@@ -263,7 +263,7 @@ bool XMLParser::vparseIntegerKey(const char *key, int count, va_list args) {
 	int *num_ptr;
 
 	while (count--) {
-		while (isspace(*key))
+		while (isspace(static_cast<unsigned char>(*key)))
 			key++;
 
 		num_ptr = va_arg(args, int*);
@@ -271,7 +271,7 @@ bool XMLParser::vparseIntegerKey(const char *key, int count, va_list args) {
 
 		key = parseEnd;
 
-		while (isspace(*key))
+		while (isspace(static_cast<unsigned char>(*key)))
 			key++;
 
 		if (count && *key++ != ',')
@@ -463,10 +463,10 @@ bool XMLParser::parse() {
 }
 
 bool XMLParser::skipSpaces() {
-	if (!isspace(_char))
+	if (!isspace(static_cast<unsigned char>(_char)))
 		return false;
 
-	while (_char && isspace(_char))
+	while (_char && isspace(static_cast<unsigned char>(_char)))
 		_char = _stream->readByte();
 
 	return true;
@@ -516,7 +516,7 @@ bool XMLParser::parseToken() {
 		_char = _stream->readByte();
 	}
 
-	return isspace(_char) != 0 || _char == '>' || _char == '=' || _char == '/';
+	return isspace(static_cast<unsigned char>(_char)) != 0 || _char == '>' || _char == '=' || _char == '/';
 }
 
 } // End of namespace Common
diff --git a/common/xmlparser.h b/common/xmlparser.h
index 7923e43a37..40c779b87e 100644
--- a/common/xmlparser.h
+++ b/common/xmlparser.h
@@ -294,7 +294,7 @@ protected:
 	 * in their name.
 	 */
 	virtual inline bool isValidNameChar(char c) {
-		return isalnum(c) || c == '_';
+		return isalnum(static_cast<unsigned char>(c)) || c == '_';
 	}
 
 	/**
diff --git a/engines/agi/wagparser.cpp b/engines/agi/wagparser.cpp
index 14159c0147..39f9e0dd92 100644
--- a/engines/agi/wagparser.cpp
+++ b/engines/agi/wagparser.cpp
@@ -112,11 +112,11 @@ WagFileParser::~WagFileParser() {
 bool WagFileParser::checkAgiVersionProperty(const WagProperty &version) const {
 	if (version.getCode() == WagProperty::PC_INTVERSION && // Must be AGI interpreter version property
 		version.getSize() >= 3 && // Need at least three characters for a version number like "X.Y"
-		isdigit(version.getData()[0]) && // And the first character must be a digit
+		isdigit(static_cast<unsigned char>(version.getData()[0])) && // And the first character must be a digit
 		(version.getData()[1] == ',' || version.getData()[1] == '.')) { // And the second a comma or a period
 
 		for (int i = 2; i < version.getSize(); i++) // And the rest must all be digits
-			if (!isdigit(version.getData()[i]))
+			if (!isdigit(static_cast<unsigned char>(version.getData()[i])))
 				return false; // Bail out if found a non-digit after the decimal point
 
 		return true;
diff --git a/engines/agos/script_pn.cpp b/engines/agos/script_pn.cpp
index bde59b71b8..3bd8ce19a3 100644
--- a/engines/agos/script_pn.cpp
+++ b/engines/agos/script_pn.cpp
@@ -465,8 +465,8 @@ void AGOSEngine_PN::opn_opcode35() {
 void AGOSEngine_PN::opn_opcode36() {
 	for (int i = 0; i < _dataBase[57] + 1; ++i)
 		_wordcp[i] = 0;
-	if (isspace(*_inpp))
-		while ((*_inpp) && (isspace(*_inpp)))
+	if (isspace(static_cast<unsigned char>(*_inpp)))
+		while ((*_inpp) && (isspace(static_cast<unsigned char>(*_inpp))))
 			_inpp++;
 	if (*_inpp == 0) {
 		setScriptReturn(false);
@@ -480,7 +480,7 @@ void AGOSEngine_PN::opn_opcode36() {
 	}
 
 	int ct = 1;
-	while ((*_inpp != '.') && (*_inpp != ',') && (!isspace(*_inpp)) && (*_inpp != '\0') &&
+	while ((*_inpp != '.') && (*_inpp != ',') && (!isspace(static_cast<unsigned char>(*_inpp))) && (*_inpp != '\0') &&
 		(*_inpp!='"')) {
 		if (ct < _dataBase[57])
 			_wordcp[ct++] = *_inpp;
@@ -580,7 +580,7 @@ void AGOSEngine_PN::opn_opcode46() {
 		return;
 	}
 	x++;
-	while ((*x != '.') && (*x != ',') && (*x != '"') && (!isspace(*x)) && (*x != '\0'))
+	while ((*x != '.') && (*x != ',') && (*x != '"') && (!isspace(static_cast<unsigned char>(*x))) && (*x != '\0'))
 		pcf(*x++);
 	setScriptReturn(true);
 }
diff --git a/engines/cine/detection.cpp b/engines/cine/detection.cpp
index cffeb29418..ba0251520b 100644
--- a/engines/cine/detection.cpp
+++ b/engines/cine/detection.cpp
@@ -141,7 +141,7 @@ SaveStateList CineMetaEngine::listSaves(const char *target) const {
 
 		for (file = filenames.begin(); file != filenames.end(); ++file) {
 			// Jump over savegame files that don't end with a digit (e.g. "fw.3" is ok, "fw.a" is not).
-			if (!isdigit(file->lastChar()))
+			if (!isdigit(static_cast<unsigned char>(file->lastChar())))
 				continue;
 
 			// Obtain the last digit of the filename, since they correspond to the save slot
diff --git a/engines/drascula/interface.cpp b/engines/drascula/interface.cpp
index eb36baed18..e3a97087c0 100644
--- a/engines/drascula/interface.cpp
+++ b/engines/drascula/interface.cpp
@@ -159,7 +159,7 @@ void DrasculaEngine::enterName() {
 		key = getScan();
 
 		if (key != 0) {
-			if (key >= 0 && key <= 0xFF && isalpha(key))
+			if (key >= 0 && key <= 0xFF && isalpha(static_cast<unsigned char>(key)))
 				select2[v] = tolower(key);
 			else if ((key >= Common::KEYCODE_0 && key <= Common::KEYCODE_9) || key == Common::KEYCODE_SPACE)
 				select2[v] = key;
diff --git a/engines/hugo/parser.cpp b/engines/hugo/parser.cpp
index 5cb97f2dc5..38a8e4e3ff 100644
--- a/engines/hugo/parser.cpp
+++ b/engines/hugo/parser.cpp
@@ -235,7 +235,7 @@ void Parser::charHandler() {
 			if (_cmdLineIndex >= kMaxLineSize) {
 				//MessageBeep(MB_ICONASTERISK);
 				warning("STUB: MessageBeep() - Command line too long");
-			} else if (isprint(c)) {
+			} else if (isprint(static_cast<unsigned char>(c))) {
 				_cmdLine[_cmdLineIndex++] = c;
 				_cmdLine[_cmdLineIndex] = '\0';
 			}
diff --git a/engines/hugo/util.cpp b/engines/hugo/util.cpp
index a936a23de1..6dc9890c3a 100644
--- a/engines/hugo/util.cpp
+++ b/engines/hugo/util.cpp
@@ -119,7 +119,7 @@ char *strlwr(char *buffer) {
 	char *result = buffer;
 
 	while (*buffer != '\0') {
-		if (isupper(*buffer))
+		if (isupper(static_cast<unsigned char>(*buffer)))
 			*buffer = tolower(*buffer);
 		buffer++;
 	}
diff --git a/engines/kyra/gui.cpp b/engines/kyra/gui.cpp
index f58ca0117c..29cbe20b23 100644
--- a/engines/kyra/gui.cpp
+++ b/engines/kyra/gui.cpp
@@ -375,7 +375,7 @@ void GUI::updateSaveList(bool excludeQuickSaves) {
 		s1 = (*i)[i->size()-3];
 		s2 = (*i)[i->size()-2];
 		s3 = (*i)[i->size()-1];
-		if (!isdigit(s1) || !isdigit(s2) || !isdigit(s3))
+		if (!isdigit(static_cast<unsigned char>(s1)) || !isdigit(static_cast<unsigned char>(s2)) || !isdigit(static_cast<unsigned char>(s3)))
 			continue;
 		s1 -= '0';
 		s2 -= '0';
diff --git a/engines/m4/dialogs.cpp b/engines/m4/dialogs.cpp
index 390ca711d1..2b2c479673 100644
--- a/engines/m4/dialogs.cpp
+++ b/engines/m4/dialogs.cpp
@@ -265,7 +265,7 @@ void Dialog::setupInputArea() {
  */
 bool Dialog::matchCommand(const char *s1, const char *s2) {
 	bool result = scumm_strnicmp(s1, s2, strlen(s2)) == 0;
-	_commandCase = isupper(*s1);
+	_commandCase = isupper(static_cast<unsigned char>(*s1));
 	return result;
 }
 
diff --git a/engines/parallaction/parser_br.cpp b/engines/parallaction/parser_br.cpp
index f53d71caec..df53ecca3f 100644
--- a/engines/parallaction/parser_br.cpp
+++ b/engines/parallaction/parser_br.cpp
@@ -524,14 +524,14 @@ DECLARE_COMMAND_PARSER(location)  {
 	ctxt.cmd->_startPos.x = -1000;
 	ctxt.cmd->_startPos2.x = -1000;
 	if (_tokens[ctxt.nextToken][0] != '\0') {
-		if (isdigit(_tokens[ctxt.nextToken][0]) || _tokens[ctxt.nextToken][0] == '-') {
+		if (isdigit(static_cast<unsigned char>(_tokens[ctxt.nextToken][0])) || _tokens[ctxt.nextToken][0] == '-') {
 			ctxt.cmd->_startPos.x = atoi(_tokens[ctxt.nextToken]);
 			ctxt.nextToken++;
 			ctxt.cmd->_startPos.y = atoi(_tokens[ctxt.nextToken]);
 			ctxt.nextToken++;
 		}
 
-		if (isdigit(_tokens[ctxt.nextToken][0]) || _tokens[ctxt.nextToken][0] == '-') {
+		if (isdigit(static_cast<unsigned char>(_tokens[ctxt.nextToken][0])) || _tokens[ctxt.nextToken][0] == '-') {
 			ctxt.cmd->_startPos2.x = atoi(_tokens[ctxt.nextToken]);
 			ctxt.nextToken++;
 			ctxt.cmd->_startPos2.y = atoi(_tokens[ctxt.nextToken]);
@@ -677,7 +677,7 @@ DECLARE_COMMAND_PARSER(text)  {
 
 	createCommand(_parser->_lookup);
 
-	if (isdigit(_tokens[1][1])) {
+	if (isdigit(static_cast<unsigned char>(_tokens[1][1]))) {
 		ctxt.cmd->_zeta0 = atoi(_tokens[1]);
 		ctxt.nextToken++;
 	} else {
@@ -714,7 +714,7 @@ DECLARE_COMMAND_PARSER(unary)  {
 DECLARE_ZONE_PARSER(limits)  {
 	debugC(7, kDebugParser, "ZONE_PARSER(limits) ");
 
-	if (isalpha(_tokens[1][1])) {
+	if (isalpha(static_cast<unsigned char>(_tokens[1][1]))) {
 		ctxt.z->_flags |= kFlagsAnimLinked;
 		ctxt.z->_linkedName = _tokens[1];
 	} else {
@@ -1003,7 +1003,7 @@ DECLARE_INSTRUCTION_PARSER(text)  {
 
 	int _si = 1;
 
-	if (isdigit(_tokens[1][1])) {
+	if (isdigit(static_cast<unsigned char>(_tokens[1][1]))) {
 		ctxt.inst->_y = atoi(_tokens[1]);
 		_si = 2;
 	} else {
@@ -1066,7 +1066,7 @@ DECLARE_INSTRUCTION_PARSER(endif)  {
 
 void ProgramParser_br::parseRValue(ScriptVar &v, const char *str) {
 
-	if (isdigit(str[0]) || str[0] == '-') {
+	if (isdigit(static_cast<unsigned char>(str[0])) || str[0] == '-') {
 		v.setImmediate(atoi(str));
 		return;
 	}
diff --git a/engines/parallaction/parser_ns.cpp b/engines/parallaction/parser_ns.cpp
index 213f0ae191..100b608172 100644
--- a/engines/parallaction/parser_ns.cpp
+++ b/engines/parallaction/parser_ns.cpp
@@ -534,7 +534,7 @@ DECLARE_INSTRUCTION_PARSER(endscript)  {
 
 void ProgramParser_ns::parseRValue(ScriptVar &v, const char *str) {
 
-	if (isdigit(str[0]) || str[0] == '-') {
+	if (isdigit(static_cast<unsigned char>(str[0])) || str[0] == '-') {
 		v.setImmediate(atoi(str));
 		return;
 	}
diff --git a/engines/queen/talk.cpp b/engines/queen/talk.cpp
index b83bf60435..1f8d9b29f9 100644
--- a/engines/queen/talk.cpp
+++ b/engines/queen/talk.cpp
@@ -658,7 +658,7 @@ void Talk::stringAnimation(const SpeechParameters *parameters, int startFrame, i
 	} else if (parameters->animation[0] == 'E') {
 		// Talking head animation
 		return;
-	} else if (!isdigit(parameters->animation[0])) {
+	} else if (!isdigit(static_cast<unsigned char>(parameters->animation[0]))) {
 		debug(6, "Error in speak string animation: '%s'", parameters->animation);
 		return;
 	} else
diff --git a/engines/sci/engine/kstring.cpp b/engines/sci/engine/kstring.cpp
index 07b87a7cbc..9f10691767 100644
--- a/engines/sci/engine/kstring.cpp
+++ b/engines/sci/engine/kstring.cpp
@@ -238,14 +238,14 @@ reg_t kFormat(EngineState *s, int argc, reg_t *argv) {
 
 			/* int writelength; -- unused atm */
 
-			if (xfer && (isdigit(xfer) || xfer == '-' || xfer == '=')) {
+			if (xfer && (isdigit(static_cast<unsigned char>(xfer)) || xfer == '-' || xfer == '=')) {
 				char *destp;
 
 				if (xfer == '0')
 					fillchar = '0';
 				else if (xfer == '=')
 					align = ALIGN_CENTER;
-				else if (isdigit(xfer) || (xfer == '-'))
+				else if (isdigit(static_cast<unsigned char>(xfer)) || (xfer == '-'))
 					source--; // Go to start of length argument
 
 				str_leng = strtol(source, &destp, 10);
diff --git a/engines/sci/graphics/text16.cpp b/engines/sci/graphics/text16.cpp
index c2f71a0e54..84547d9828 100644
--- a/engines/sci/graphics/text16.cpp
+++ b/engines/sci/graphics/text16.cpp
@@ -100,7 +100,7 @@ int16 GfxText16::CodeProcessing(const char *&text, GuiResourceId orgFontId, int1
 	//  cX -> sets textColor to _textColors[X-1]
 	curCode = textCode[0];
 	curCodeParm = textCode[1];
-	if (isdigit(curCodeParm)) {
+	if (isdigit(static_cast<unsigned char>(curCodeParm))) {
 		curCodeParm -= '0';
 	} else {
 		curCodeParm = -1;
diff --git a/engines/sci/resource.cpp b/engines/sci/resource.cpp
index fa70481bdc..f18b6c91f5 100644
--- a/engines/sci/resource.cpp
+++ b/engines/sci/resource.cpp
@@ -1555,7 +1555,7 @@ void ResourceManager::readResourcePatches() {
 			name = (*x)->getName();
 
 			// SCI1 scheme
-			if (isdigit(name[0])) {
+			if (isdigit(static_cast<unsigned char>(name[0]))) {
 				char *end = 0;
 				resourceNr = strtol(name.c_str(), &end, 10);
 				bAdd = (*end == '.'); // Ensure the next character is the period
@@ -1563,7 +1563,7 @@ void ResourceManager::readResourcePatches() {
 				// SCI0 scheme
 				int resname_len = strlen(szResType);
 				if (scumm_strnicmp(name.c_str(), szResType, resname_len) == 0
-					&& !isalpha(name[resname_len + 1])) {
+					&& !isalpha(static_cast<unsigned char>(name[resname_len + 1]))) {
 					resourceNr = atoi(name.c_str() + resname_len + 1);
 					bAdd = true;
 				}
diff --git a/engines/sci/resource_audio.cpp b/engines/sci/resource_audio.cpp
index 032040fc2c..f3a3c8dd5b 100644
--- a/engines/sci/resource_audio.cpp
+++ b/engines/sci/resource_audio.cpp
@@ -197,7 +197,7 @@ void ResourceManager::readWaveAudioPatches() {
 	for (Common::ArchiveMemberList::const_iterator x = files.begin(); x != files.end(); ++x) {
 		Common::String name = (*x)->getName();
 
-		if (isdigit(name[0]))
+		if (isdigit(static_cast<unsigned char>(name[0])))
 			processWavePatch(ResourceId(kResourceTypeAudio, atoi(name.c_str())), name);
 	}
 }
diff --git a/engines/scumm/smush/smush_player.cpp b/engines/scumm/smush/smush_player.cpp
index 66502572de..2f4e86bf61 100644
--- a/engines/scumm/smush/smush_player.cpp
+++ b/engines/scumm/smush/smush_player.cpp
@@ -90,13 +90,13 @@ public:
 			assert(def_end != NULL);
 
 			char *id_end = def_end;
-			while (id_end >= def_start && !isdigit(*(id_end-1))) {
+			while (id_end >= def_start && !isdigit(static_cast<unsigned char>(*(id_end-1)))) {
 				id_end--;
 			}
 
 			assert(id_end > def_start);
 			char *id_start = id_end;
-			while (isdigit(*(id_start - 1))) {
+			while (isdigit(static_cast<unsigned char>(*(id_start - 1)))) {
 				id_start--;
 			}
 
diff --git a/engines/scumm/string.cpp b/engines/scumm/string.cpp
index 4b3207c6bf..2d2209c155 100644
--- a/engines/scumm/string.cpp
+++ b/engines/scumm/string.cpp
@@ -1383,10 +1383,10 @@ void ScummEngine_v7::loadLanguageBundle() {
 			} else if (*ptr == '#') {
 				// Number of subtags following a given basetag. We don't need that
 				// information so we just skip it
-			} else if (isdigit(*ptr)) {
+			} else if (isdigit(static_cast<unsigned char>(*ptr))) {
 				int idx = 0;
 				// A number (up to three digits)...
-				while (isdigit(*ptr)) {
+				while (isdigit(static_cast<unsigned char>(*ptr))) {
 					idx = idx * 10 + (*ptr - '0');
 					ptr++;
 				}
@@ -1424,12 +1424,12 @@ void ScummEngine_v7::loadLanguageBundle() {
 		for (i = 0; i < _languageIndexSize; i++) {
 			// First 8 chars in the line give the string ID / 'tag'
 			int j;
-			for (j = 0; j < 8 && !isspace(*ptr); j++, ptr++)
+			for (j = 0; j < 8 && !isspace(static_cast<unsigned char>(*ptr)); j++, ptr++)
 				_languageIndex[i].tag[j] = toupper(*ptr);
 			_languageIndex[i].tag[j] = 0;
 
 			// After that follows a single space which we skip
-			assert(isspace(*ptr));
+			assert(isspace(static_cast<unsigned char>(*ptr)));
 			ptr++;
 
 			// Then comes the translated string: we record an offset to that.
diff --git a/engines/sky/detection.cpp b/engines/sky/detection.cpp
index f3cce06ad6..a1067496da 100644
--- a/engines/sky/detection.cpp
+++ b/engines/sky/detection.cpp
@@ -206,7 +206,7 @@ SaveStateList SkyMetaEngine::listSaves(const char *target) const {
 		// Extract the extension
 		Common::String ext = file->c_str() + file->size() - 3;
 		ext.toUppercase();
-		if (isdigit(ext[0]) && isdigit(ext[1]) && isdigit(ext[2])){
+		if (isdigit(static_cast<unsigned char>(ext[0])) && isdigit(static_cast<unsigned char>(ext[1])) && isdigit(static_cast<unsigned char>(ext[2]))){
 			int slotNum = atoi(ext.c_str());
 			Common::InSaveFile *in = saveFileMan->openForLoading(*file);
 			if (in) {
diff --git a/engines/sword1/animation.cpp b/engines/sword1/animation.cpp
index 4ce3e2e88d..f19efd2635 100644
--- a/engines/sword1/animation.cpp
+++ b/engines/sword1/animation.cpp
@@ -114,7 +114,7 @@ bool MoviePlayer::load(uint32 id) {
 				int startFrame = strtoul(ptr, const_cast<char **>(&ptr), 10);
 				int endFrame = strtoul(ptr, const_cast<char **>(&ptr), 10);
 
-				while (*ptr && isspace(*ptr))
+				while (*ptr && isspace(static_cast<unsigned char>(*ptr)))
 					ptr++;
 
 				if (startFrame > endFrame) {
diff --git a/engines/sword25/util/lua/llex.cpp b/engines/sword25/util/lua/llex.cpp
index 4d73a6a600..b456ee2dfe 100644
--- a/engines/sword25/util/lua/llex.cpp
+++ b/engines/sword25/util/lua/llex.cpp
@@ -188,7 +188,7 @@ static void trydecpoint (LexState *ls, SemInfo *seminfo) {
   sprintf(buf, "%.1f", 1.0);
   ls->decpoint = '.';
   for (i = 0; buf[i]; i++) {
-    if (!isspace(buf[i]) && !isdigit(buf[i])) {
+    if (!isspace(static_cast<unsigned char>(buf[i])) && !isdigit(static_cast<unsigned char>(buf[i]))) {
       ls->decpoint = buf[i];
       break;
     }
diff --git a/engines/touche/menu.cpp b/engines/touche/menu.cpp
index f469a95803..c58e2f1a33 100644
--- a/engines/touche/menu.cpp
+++ b/engines/touche/menu.cpp
@@ -103,7 +103,7 @@ struct MenuData {
 	void addCharToDescription(int slot, char chr) {
 		char *description = saveLoadDescriptionsTable[slot];
 		int descriptionLen = strlen(description);
-		if (descriptionLen < 32 && isprint(chr)) {
+		if (descriptionLen < 32 && isprint(static_cast<unsigned char>(chr))) {
 			description[descriptionLen] = chr;
 			description[descriptionLen + 1] = 0;
 		}
diff --git a/graphics/font.cpp b/graphics/font.cpp
index d254c64264..0c180ee47d 100644
--- a/graphics/font.cpp
+++ b/graphics/font.cpp
@@ -948,7 +948,7 @@ int Font::wordWrapText(const Common::String &str, int maxWidth, Common::Array<Co
 			if (lineWidth > 0) {
 				wrapper.add(line, lineWidth);
 				// Trim left side
-				while (tmpStr.size() && isspace(tmpStr[0])) {
+				while (tmpStr.size() && isspace(static_cast<unsigned char>(tmpStr[0]))) {
 					tmpWidth -= getCharWidth(tmpStr[0]);
 					tmpStr.deleteChar(0);
 				}