diff --git a/include/common/standard.h b/include/common/standard.h
index 6d2432f99..3d9083c1d 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -378,7 +378,7 @@ extern const char *invalid_prefix_char(const char *name);
  */
 static inline int is_idchar(char c)
 {
-	return isalnum((int)(unsigned char)c) ||
+	return isalnum((unsigned char)c) ||
 	       c == '.' || c == '_' || c == '-' || c == '+' || c == ':';
 }
 
diff --git a/src/buffer.c b/src/buffer.c
index c4d614051..6211d147c 100644
--- a/src/buffer.c
+++ b/src/buffer.c
@@ -85,7 +85,7 @@ void buffer_dump(FILE *o, struct buffer *b, int from, int to)
 		}
 		fprintf(o, "  ");
 		for (i = 0; (from + i < to) && (i < 16) ; i++) {
-			fprintf(o, "%c", isprint((int)b_orig(b)[from + i]) ? b_orig(b)[from + i] : '.') ;
+			fprintf(o, "%c", isprint((unsigned char)b_orig(b)[from + i]) ? b_orig(b)[from + i] : '.') ;
 			if ((((from + i) & 15) == 15) && ((from + i) != to-1))
 				fprintf(o, "\n");
 		}
diff --git a/src/cfgparse-listen.c b/src/cfgparse-listen.c
index 3c2978c8a..bd2275238 100644
--- a/src/cfgparse-listen.c
+++ b/src/cfgparse-listen.c
@@ -1009,7 +1009,7 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int kwm)
 				}
 				val = args[cur_arg + 1];
 				while (*val) {
-					if (iscntrl(*val) || *val == ';') {
+					if (iscntrl((unsigned char)*val) || *val == ';') {
 						ha_alert("parsing [%s:%d]: character '%%x%02X' is not permitted in attribute value.\n",
 							 file, linenum, *val);
 						err_code |= ERR_ALERT | ERR_FATAL;
@@ -3649,11 +3649,11 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int kwm)
 					char *name, *end;
 
 					name = args[cur_arg+1] + 7;
-					while (isspace(*name))
+					while (isspace((unsigned char)*name))
 						name++;
 
 					end = name;
-					while (*end && !isspace(*end) && *end != ',' && *end != ')')
+					while (*end && !isspace((unsigned char)*end) && *end != ',' && *end != ')')
 						end++;
 
 					curproxy->conn_src.opts &= ~CO_SRC_TPROXY_MASK;
@@ -3665,14 +3665,14 @@ int cfg_parse_listen(const char *file, int linenum, char **args, int kwm)
 					curproxy->conn_src.bind_hdr_occ = -1;
 
 					/* now look for an occurrence number */
-					while (isspace(*end))
+					while (isspace((unsigned char)*end))
 						end++;
 					if (*end == ',') {
 						end++;
 						name = end;
 						if (*end == '-')
 							end++;
-						while (isdigit((int)*end))
+						while (isdigit((unsigned char)*end))
 							end++;
 						curproxy->conn_src.bind_hdr_occ = strl2ic(name, end-name);
 					}
diff --git a/src/cfgparse.c b/src/cfgparse.c
index 68cb0e980..cd3990494 100644
--- a/src/cfgparse.c
+++ b/src/cfgparse.c
@@ -374,7 +374,7 @@ int parse_process_number(const char *arg, unsigned long *proc, int max, int *aut
 		for (p = arg; *p; p++) {
 			if (*p == '-' && !dash)
 				dash = p;
-			else if (!isdigit((int)*p)) {
+			else if (!isdigit((unsigned char)*p)) {
 				memprintf(err, "'%s' is not a valid number/range.", arg);
 				return -1;
 			}
@@ -420,7 +420,7 @@ unsigned long parse_cpu_set(const char **args, unsigned long *cpu_set, char **er
 		char        *dash;
 		unsigned int low, high;
 
-		if (!isdigit((int)*args[cur_arg])) {
+		if (!isdigit((unsigned char)*args[cur_arg])) {
 			memprintf(err, "'%s' is not a CPU range.\n", args[cur_arg]);
 			return -1;
 		}
@@ -2035,13 +2035,13 @@ int readcfgfile(const char *file)
 					braces = 1;
 				}
 
-				if (!isalpha((int)(unsigned char)*var_beg) && *var_beg != '_') {
+				if (!isalpha((unsigned char)*var_beg) && *var_beg != '_') {
 					ha_alert("parsing [%s:%d] : Variable expansion: Unrecognized character '%c' in variable name.\n", file, linenum, *var_beg);
 					err_code |= ERR_ALERT | ERR_FATAL;
 					goto next_line; /* skip current line */
 				}
 
-				while (isalnum((int)(unsigned char)*var_end) || *var_end == '_')
+				while (isalnum((unsigned char)*var_end) || *var_end == '_')
 					var_end++;
 
 				save_char = *var_end;
diff --git a/src/chunk.c b/src/chunk.c
index 8e77858c3..100783e23 100644
--- a/src/chunk.c
+++ b/src/chunk.c
@@ -193,7 +193,7 @@ int chunk_htmlencode(struct buffer *dst, struct buffer *src)
 
 		c = src->area[i];
 
-		if (!isascii(c) || !isprint((unsigned char)c) || c == '&' || c == '"' || c == '\'' || c == '<' || c == '>') {
+		if (!isascii((unsigned char)c) || !isprint((unsigned char)c) || c == '&' || c == '"' || c == '\'' || c == '<' || c == '>') {
 			l = snprintf(dst->area + dst->data, free, "&#%u;",
 				     (unsigned char)c);
 
@@ -235,7 +235,7 @@ int chunk_asciiencode(struct buffer *dst, struct buffer *src, char qc)
 
 		c = src->area[i];
 
-		if (!isascii(c) || !isprint((unsigned char)c) || c == '<' || c == '>' || c == qc) {
+		if (!isascii((unsigned char)c) || !isprint((unsigned char)c) || c == '<' || c == '>' || c == qc) {
 			l = snprintf(dst->area + dst->data, free, "<%02X>",
 				     (unsigned char)c);
 
diff --git a/src/fcgi-app.c b/src/fcgi-app.c
index a9466a577..5d2658096 100644
--- a/src/fcgi-app.c
+++ b/src/fcgi-app.c
@@ -54,7 +54,7 @@ static struct ist fcgi_param_name(char *dst, const struct ist name)
 	memcpy(dst, ":fcgi-", 6);
 	ofs1 = 6;
 	for (ofs2 = 0; ofs2 < name.len; ofs2++) {
-		if (isalnum((int)name.ptr[ofs2]))
+		if (isalnum((unsigned char)name.ptr[ofs2]))
 			dst[ofs1++] = ist_lc[(unsigned char)name.ptr[ofs2]];
 		else
 			dst[ofs1++] = '_';
diff --git a/src/fcgi.c b/src/fcgi.c
index 33aa2a249..cb7b44e79 100644
--- a/src/fcgi.c
+++ b/src/fcgi.c
@@ -135,7 +135,7 @@ int fcgi_encode_param(struct buffer *out, const struct fcgi_param *p)
 	}
 
 	for (off = 0; off < p->n.len; off++) {
-		if (isalnum((int)p->n.ptr[off]))
+		if (isalnum((unsigned char)p->n.ptr[off]))
 			out->area[len++] = ist_uc[(unsigned char)p->n.ptr[off]];
 		else
 			out->area[len++] = '_';
diff --git a/src/flt_spoe.c b/src/flt_spoe.c
index a78e6159e..ecad5c446 100644
--- a/src/flt_spoe.c
+++ b/src/flt_spoe.c
@@ -344,7 +344,7 @@ spoe_str_to_vsn(const char *str, size_t len)
 	vsn = -1;
 
 	/* skip leading spaces */
-	while (p < end && isspace(*p))
+	while (p < end && isspace((unsigned char)*p))
 		p++;
 
 	/* parse Major number, until the '.' */
@@ -378,7 +378,7 @@ spoe_str_to_vsn(const char *str, size_t len)
 		goto out;
 
 	/* skip trailing spaces */
-	while (p < end && isspace(*p))
+	while (p < end && isspace((unsigned char)*p))
 		p++;
 	if (p != end)
 		goto out;
@@ -784,21 +784,21 @@ spoe_handle_agenthello_frame(struct appctx *appctx, char *frame, size_t size)
 				char *delim;
 
 				/* Skip leading spaces */
-				for (; isspace(*str) && sz; str++, sz--);
+				for (; isspace((unsigned char)*str) && sz; str++, sz--);
 
 				if (sz >= 10 && !strncmp(str, "pipelining", 10)) {
 					str += 10; sz -= 10;
-					if (!sz || isspace(*str) || *str == ',')
+					if (!sz || isspace((unsigned char)*str) || *str == ',')
 						flags |= SPOE_APPCTX_FL_PIPELINING;
 				}
 				else if (sz >= 5 && !strncmp(str, "async", 5)) {
 					str += 5; sz -= 5;
-					if (!sz || isspace(*str) || *str == ',')
+					if (!sz || isspace((unsigned char)*str) || *str == ',')
 						flags |= SPOE_APPCTX_FL_ASYNC;
 				}
 				else if (sz >= 13 && !strncmp(str, "fragmentation", 13)) {
 					str += 13; sz -= 13;
-					if (!sz || isspace(*str) || *str == ',')
+					if (!sz || isspace((unsigned char)*str) || *str == ',')
 						flags |= SPOE_APPCTX_FL_FRAGMENTATION;
 				}
 
@@ -3587,7 +3587,7 @@ cfg_parse_spoe_agent(const char *file, int linenum, char **args, int kwm)
 				goto out;
 			tmp = args[2];
 			while (*tmp) {
-				if (!isalnum(*tmp) && *tmp != '_' && *tmp != '.') {
+				if (!isalnum((unsigned char)*tmp) && *tmp != '_' && *tmp != '.') {
 					ha_alert("parsing [%s:%d]: '%s %s' only supports [a-zA-Z0-9_.] chars.\n",
 						 file, linenum, args[0], args[1]);
 					err_code |= ERR_ALERT | ERR_FATAL;
@@ -3621,7 +3621,7 @@ cfg_parse_spoe_agent(const char *file, int linenum, char **args, int kwm)
 				goto out;
 			tmp = args[2];
 			while (*tmp) {
-				if (!isalnum(*tmp) && *tmp != '_' && *tmp != '.') {
+				if (!isalnum((unsigned char)*tmp) && *tmp != '_' && *tmp != '.') {
 					ha_alert("parsing [%s:%d]: '%s %s' only supports [a-zA-Z0-9_.] chars.\n",
 						 file, linenum, args[0], args[1]);
 					err_code |= ERR_ALERT | ERR_FATAL;
@@ -3645,7 +3645,7 @@ cfg_parse_spoe_agent(const char *file, int linenum, char **args, int kwm)
 				goto out;
 			tmp = args[2];
 			while (*tmp) {
-				if (!isalnum(*tmp) && *tmp != '_' && *tmp != '.') {
+				if (!isalnum((unsigned char)*tmp) && *tmp != '_' && *tmp != '.') {
 					ha_alert("parsing [%s:%d]: '%s %s' only supports [a-zA-Z0-9_.] chars.\n",
 						 file, linenum, args[0], args[1]);
 					err_code |= ERR_ALERT | ERR_FATAL;
@@ -3669,7 +3669,7 @@ cfg_parse_spoe_agent(const char *file, int linenum, char **args, int kwm)
 				goto out;
 			tmp = args[2];
 			while (*tmp) {
-				if (!isalnum(*tmp) && *tmp != '_' && *tmp != '.') {
+				if (!isalnum((unsigned char)*tmp) && *tmp != '_' && *tmp != '.') {
 					ha_alert("parsing [%s:%d]: '%s %s' only supports [a-zA-Z0-9_.] chars.\n",
 						 file, linenum, args[0], args[1]);
 					err_code |= ERR_ALERT | ERR_FATAL;
@@ -4185,7 +4185,7 @@ parse_spoe_flt(char **args, int *cur_arg, struct proxy *px,
 		char *tmp = curagent->id;
 
 		while (*tmp) {
-			if (!isalnum(*tmp) && *tmp != '_' && *tmp != '.') {
+			if (!isalnum((unsigned char)*tmp) && *tmp != '_' && *tmp != '.') {
 				memprintf(err, "Invalid variable prefix '%s' for SPOE agent '%s' declared at %s:%d. "
 					  "Use 'option var-prefix' to set it. Only [a-zA-Z0-9_.] chars are supported.\n",
 					  curagent->id, curagent->id, curagent->conf.file, curagent->conf.line);
diff --git a/src/flt_trace.c b/src/flt_trace.c
index e349431a6..437f283a5 100644
--- a/src/flt_trace.c
+++ b/src/flt_trace.c
@@ -103,7 +103,7 @@ trace_hexdump(struct ist ist)
                 if (i % 16 == 15) {
                         fprintf(stderr, "  |");
                         for(j = i - 15; j <= i && j < ist.len; j++)
-				fprintf(stderr, "%c", (isprint(*(ist.ptr+j)) ? *(ist.ptr+j) : '.'));
+				fprintf(stderr, "%c", (isprint((unsigned char)*(ist.ptr+j)) ? *(ist.ptr+j) : '.'));
                         fprintf(stderr, "|\n");
                 }
         }
diff --git a/src/haproxy.c b/src/haproxy.c
index f04ccea6e..e23d28349 100644
--- a/src/haproxy.c
+++ b/src/haproxy.c
@@ -1680,7 +1680,7 @@ static void init(int argc, char **argv)
 							 *argv, strerror(errno));
 						exit(1);
 					} else if (endptr && strlen(endptr)) {
-						while (isspace(*endptr)) endptr++;
+						while (isspace((unsigned char)*endptr)) endptr++;
 						if (*endptr != 0) {
 							ha_alert("-%2s option: some bytes unconsumed in PID list {%s}\n",
 								 flag, endptr);
diff --git a/src/hlua.c b/src/hlua.c
index 4c5598d8e..d8e538b63 100644
--- a/src/hlua.c
+++ b/src/hlua.c
@@ -838,7 +838,7 @@ static inline void hlua_sendlog(struct proxy *px, int level, const char *msg)
 			*(p-1) = '.';
 			break;
 		}
-		if (isprint(*msg))
+		if (isprint((unsigned char)*msg))
 			*p = *msg;
 		else
 			*p = '.';
diff --git a/src/http_htx.c b/src/http_htx.c
index f6e224305..d5239671b 100644
--- a/src/http_htx.c
+++ b/src/http_htx.c
@@ -1953,7 +1953,7 @@ int val_blk_arg(struct arg *arg, char **err_msg)
 		int pos;
 
 		for (pos = 0; pos < arg[0].data.str.data; pos++) {
-			if (!isdigit(arg[0].data.str.area[pos])) {
+			if (!isdigit((unsigned char)arg[0].data.str.area[pos])) {
 				memprintf(err_msg, "invalid block position");
 				return 0;
 			}
diff --git a/src/log.c b/src/log.c
index 40eac40a9..60b1a5a4d 100644
--- a/src/log.c
+++ b/src/log.c
@@ -666,7 +666,7 @@ int parse_logformat_string(const char *fmt, struct proxy *curproxy, struct list
 			else {
 				char c = *str;
 				*str = 0;
-				if (isprint(c))
+				if (isprint((unsigned char)c))
 					memprintf(err, "expected ']' after '%s', but found '%c'", var, c);
 				else
 					memprintf(err, "missing ']' after '%s'", var);
diff --git a/src/sample.c b/src/sample.c
index d3568708d..eb903ec6d 100644
--- a/src/sample.c
+++ b/src/sample.c
@@ -1466,7 +1466,7 @@ static int sample_conv_debug(const struct arg *arg_p, struct sample *smp, void *
 	/* Display the displayable chars*. */
 	b_putchr(buf, '<');
 	for (i = 0; i < tmp.data.u.str.data; i++) {
-		if (isprint(tmp.data.u.str.area[i]))
+		if (isprint((unsigned char)tmp.data.u.str.area[i]))
 			b_putchr(buf, tmp.data.u.str.area[i]);
 		else
 			b_putchr(buf, '.');
@@ -2046,7 +2046,7 @@ static int sample_conv_json(const struct arg *arg_p, struct sample *smp, void *p
 			len = 2;
 			str = "\\t";
 		}
-		else if (c > 0xff || !isprint(c)) {
+		else if (c > 0xff || !isprint((unsigned char)c)) {
 			/* isprint generate a segfault if c is too big. The man says that
 			 * c must have the value of an unsigned char or EOF.
 			 */
diff --git a/src/server.c b/src/server.c
index 959fb22e7..965570222 100644
--- a/src/server.c
+++ b/src/server.c
@@ -809,11 +809,11 @@ static int srv_parse_source(char **args, int *cur_arg,
 				char *name, *end;
 
 				name = args[*cur_arg + 1] + 7;
-				while (isspace(*name))
+				while (isspace((unsigned char)*name))
 					name++;
 
 				end = name;
-				while (*end && !isspace(*end) && *end != ',' && *end != ')')
+				while (*end && !isspace((unsigned char)*end) && *end != ',' && *end != ')')
 					end++;
 
 				newsrv->conn_src.opts &= ~CO_SRC_TPROXY_MASK;
@@ -826,14 +826,14 @@ static int srv_parse_source(char **args, int *cur_arg,
 				newsrv->conn_src.bind_hdr_occ = -1;
 
 				/* now look for an occurrence number */
-				while (isspace(*end))
+				while (isspace((unsigned char)*end))
 					end++;
 				if (*end == ',') {
 					end++;
 					name = end;
 					if (*end == '-')
 						end++;
-					while (isdigit((int)*end))
+					while (isdigit((unsigned char)*end))
 						end++;
 					newsrv->conn_src.bind_hdr_occ = strl2ic(name, end - name);
 				}
@@ -3434,7 +3434,7 @@ static void srv_state_parse_line(char *buf, const int version, char **params, ch
 	}
 
 	/* ignore blank characters at the beginning of the line */
-	while (isspace(*cur))
+	while (isspace((unsigned char)*cur))
 		++cur;
 
 	/* Ignore empty or commented lines */
@@ -3458,10 +3458,10 @@ static void srv_state_parse_line(char *buf, const int version, char **params, ch
 	arg = 1;
 	srv_arg = 0;
 	while (*cur && arg < SRV_STATE_FILE_MAX_FIELDS) {
-		if (isspace(*cur)) {
+		if (isspace((unsigned char)*cur)) {
 			*cur = '\0';
 			++cur;
-			while (isspace(*cur))
+			while (isspace((unsigned char)*cur))
 				++cur;
 			switch (version) {
 				case 1:
diff --git a/src/standard.c b/src/standard.c
index 3c4081ebb..056710c67 100644
--- a/src/standard.c
+++ b/src/standard.c
@@ -586,7 +586,7 @@ const char *invalid_char(const char *name)
 		return name;
 
 	while (*name) {
-		if (!isalnum((int)(unsigned char)*name) && *name != '.' && *name != ':' &&
+		if (!isalnum((unsigned char)*name) && *name != '.' && *name != ':' &&
 		    *name != '_' && *name != '-')
 			return name;
 		name++;
@@ -606,7 +606,7 @@ static inline const char *__invalid_char(const char *name, int (*f)(int)) {
 		return name;
 
 	while (*name) {
-		if (!f((int)(unsigned char)*name) && *name != '.' &&
+		if (!f((unsigned char)*name) && *name != '.' &&
 		    *name != '_' && *name != '-')
 			return name;
 
@@ -977,7 +977,7 @@ struct sockaddr_storage *str2sa_range(const char *str, int *port, int *low, int
 			port1 = "";
 		}
 
-		if (isdigit((int)(unsigned char)*port1)) {	/* single port or range */
+		if (isdigit((unsigned char)*port1)) {	/* single port or range */
 			port2 = strchr(port1, '-');
 			if (port2)
 				*port2++ = '\0';
@@ -3820,7 +3820,7 @@ char *env_expand(char *in)
 				var_beg++;
 
 			var_end = var_beg;
-			while (isalnum((int)(unsigned char)*var_end) || *var_end == '_') {
+			while (isalnum((unsigned char)*var_end) || *var_end == '_') {
 				var_end++;
 			}
 
@@ -4087,7 +4087,7 @@ int dump_text(struct buffer *out, const char *buf, int bsize)
 
 	while (buf[ptr] && ptr < bsize) {
 		c = buf[ptr];
-		if (isprint(c) && isascii(c) && c != '\\' && c != ' ' && c != '=') {
+		if (isprint((unsigned char)c) && isascii((unsigned char)c) && c != '\\' && c != ' ' && c != '=') {
 			if (out->data > out->size - 1)
 				break;
 			out->area[out->data++] = c;
@@ -4183,7 +4183,7 @@ void dump_hex(struct buffer *out, const char *pfx, const void *buf, int len, int
 				chunk_strcat(out, "'");
 			else if (unsafe > 1)
 				chunk_strcat(out, "*");
-			else if (isprint(d[i + j]))
+			else if (isprint((unsigned char)d[i + j]))
 				chunk_appendf(out, "%c", d[i + j]);
 			else
 				chunk_strcat(out, ".");
@@ -4214,7 +4214,7 @@ int dump_text_line(struct buffer *out, const char *buf, int bsize, int len,
 
 	while (ptr < len && ptr < bsize) {
 		c = buf[ptr];
-		if (isprint(c) && isascii(c) && c != '\\') {
+		if (isprint((unsigned char)c) && isascii((unsigned char)c) && c != '\\') {
 			if (out->data > end - 2)
 				break;
 			out->area[out->data++] = c;
diff --git a/src/stats.c b/src/stats.c
index f8a15bd54..28724fa2f 100644
--- a/src/stats.c
+++ b/src/stats.c
@@ -853,7 +853,7 @@ static int stats_dump_fields_html(struct buffer *out,
 		if (flags & STAT_SHLGNDS) {
 			chunk_appendf(out, "<div class=tips>");
 
-			if (isdigit(*field_str(stats, ST_F_ADDR)))
+			if (isdigit((unsigned char)*field_str(stats, ST_F_ADDR)))
 				chunk_appendf(out, "IPv4: %s, ", field_str(stats, ST_F_ADDR));
 			else if (*field_str(stats, ST_F_ADDR) == '[')
 				chunk_appendf(out, "IPv6: %s, ", field_str(stats, ST_F_ADDR));
@@ -958,7 +958,7 @@ static int stats_dump_fields_html(struct buffer *out,
 		if (flags & STAT_SHLGNDS) {
 			chunk_appendf(out, "<div class=tips>");
 
-			if (isdigit(*field_str(stats, ST_F_ADDR)))
+			if (isdigit((unsigned char)*field_str(stats, ST_F_ADDR)))
 				chunk_appendf(out, "IPv4: %s, ", field_str(stats, ST_F_ADDR));
 			else if (*field_str(stats, ST_F_ADDR) == '[')
 				chunk_appendf(out, "IPv6: %s, ", field_str(stats, ST_F_ADDR));
diff --git a/src/vars.c b/src/vars.c
index 63e210331..403cb69f1 100644
--- a/src/vars.c
+++ b/src/vars.c
@@ -271,7 +271,7 @@ static char *register_name(const char *name, int len, enum vars_scope *scope,
 	/* Check variable name syntax. */
 	tmp = var_names[var_names_nb - 1];
 	while (*tmp) {
-		if (!isalnum((int)(unsigned char)*tmp) && *tmp != '_' && *tmp != '.') {
+		if (!isalnum((unsigned char)*tmp) && *tmp != '_' && *tmp != '.') {
 			memprintf(err, "invalid syntax at char '%s'", tmp);
 			res = NULL;
 			goto end;