diff --git a/Zend/zend_strtod.c b/Zend/zend_strtod.c
index 1b66cada986..4b44a144292 100644
--- a/Zend/zend_strtod.c
+++ b/Zend/zend_strtod.c
@@ -3701,14 +3701,7 @@ zend_freedtoa(char *s)
  *	   calculation.
  */
 
-ZEND_API char *
-zend_dtoa
-#ifdef KR_headers
-	(dd, mode, ndigits, decpt, sign, rve)
-	double dd; int mode, ndigits, *decpt, *sign; char **rve;
-#else
-	(double dd, int mode, int ndigits, int *decpt, int *sign, char **rve)
-#endif
+ZEND_API char *zend_dtoa(double dd, int mode, int ndigits, int *decpt, bool *sign, char **rve)
 {
  /*	Arguments ndigits, decpt, sign are similar to those
 	of ecvt and fcvt; trailing zeros are suppressed from
diff --git a/Zend/zend_strtod.h b/Zend/zend_strtod.h
index ea81827df28..232a4d71e42 100644
--- a/Zend/zend_strtod.h
+++ b/Zend/zend_strtod.h
@@ -24,7 +24,7 @@
 
 BEGIN_EXTERN_C()
 ZEND_API void zend_freedtoa(char *s);
-ZEND_API char * zend_dtoa(double _d, int mode, int ndigits, int *decpt, int *sign, char **rve);
+ZEND_API char * zend_dtoa(double _d, int mode, int ndigits, int *decpt, bool *sign, char **rve);
 ZEND_API double zend_strtod(const char *s00, const char **se);
 ZEND_API double zend_hex_strtod(const char *str, const char **endptr);
 ZEND_API double zend_oct_strtod(const char *str, const char **endptr);
diff --git a/ext/standard/formatted_print.c b/ext/standard/formatted_print.c
index 0990b390d6b..71c1bbcbd93 100644
--- a/ext/standard/formatted_print.c
+++ b/ext/standard/formatted_print.c
@@ -83,7 +83,7 @@ php_sprintf_appendchars(zend_string **buffer, size_t *pos, char *add, size_t len
 inline static void
 php_sprintf_appendstring(zend_string **buffer, size_t *pos, char *add,
 						   size_t min_width, size_t max_width, char padding,
-						   size_t alignment, size_t len, int neg, int expprec, int always_sign)
+						   size_t alignment, size_t len, bool neg, int expprec, int always_sign)
 {
 	size_t npad;
 	size_t req_size;
@@ -208,7 +208,7 @@ php_sprintf_appenduint(zend_string **buffer, size_t *pos,
 
 	PRINTF_DEBUG(("sprintf: appending %d as \"%s\", i=%d\n", number, &numbuf[i], i));
 	php_sprintf_appendstring(buffer, pos, &numbuf[i], width, 0,
-							 padding, alignment, (NUM_BUF_SIZE - 1) - i, 0, 0, 0);
+							 padding, alignment, (NUM_BUF_SIZE - 1) - i, /* neg */ false, 0, 0);
 }
 /* }}} */
 
@@ -225,7 +225,7 @@ php_sprintf_appenddouble(zend_string **buffer, size_t *pos,
 	char num_buf[NUM_BUF_SIZE];
 	char *s = NULL;
 	size_t s_len = 0;
-	int is_negative = 0;
+	bool is_negative = false;
 #ifdef ZTS
 	struct lconv lconv;
 #else
@@ -346,7 +346,7 @@ php_sprintf_append2n(zend_string **buffer, size_t *pos, zend_long number,
 
 	php_sprintf_appendstring(buffer, pos, &numbuf[i], width, 0,
 							 padding, alignment, (NUM_BUF_SIZE - 1) - i,
-							 0, expprec, 0);
+							 /* neg */ false, expprec, 0);
 }
 /* }}} */
 
@@ -627,7 +627,7 @@ php_formatted_print(char *format, size_t format_len, zval *args, int argc, int n
 											 width, precision, padding,
 											 alignment,
 											 ZSTR_LEN(str),
-											 0, expprec, 0);
+											 /* neg */ false, expprec, 0);
 					zend_tmp_string_release(t);
 					break;
 				}
diff --git a/main/snprintf.c b/main/snprintf.c
index 19619fe18d9..22779801d3f 100644
--- a/main/snprintf.c
+++ b/main/snprintf.c
@@ -57,7 +57,7 @@
  * Materiel Command, USAF, under agreement number F39502-99-1-0512.
  */
 
-static char * __cvt(double value, int ndigit, int *decpt, int *sign, int fmode, int pad) /* {{{ */
+static char * __cvt(double value, int ndigit, int *decpt, bool *sign, int fmode, int pad) /* {{{ */
 {
 	register char *s = NULL;
 	char *p, *rve, c;
@@ -116,13 +116,13 @@ static char * __cvt(double value, int ndigit, int *decpt, int *sign, int fmode,
 }
 /* }}} */
 
-static inline char *php_ecvt(double value, int ndigit, int *decpt, int *sign) /* {{{ */
+static inline char *php_ecvt(double value, int ndigit, int *decpt, bool *sign) /* {{{ */
 {
 	return(__cvt(value, ndigit, decpt, sign, 0, 1));
 }
 /* }}} */
 
-static inline char *php_fcvt(double value, int ndigit, int *decpt, int *sign) /* {{{ */
+static inline char *php_fcvt(double value, int ndigit, int *decpt, bool *sign) /* {{{ */
 {
 	return(__cvt(value, ndigit, decpt, sign, 1, 1));
 }
@@ -131,7 +131,8 @@ static inline char *php_fcvt(double value, int ndigit, int *decpt, int *sign) /*
 PHPAPI char *php_gcvt(double value, int ndigit, char dec_point, char exponent, char *buf) /* {{{ */
 {
 	char *digits, *dst, *src;
-	int i, decpt, sign;
+	int i, decpt;
+	bool sign;
 	int mode = ndigit >= 0 ? 2 : 0;
 
 	if (mode == 0) {
@@ -182,7 +183,8 @@ PHPAPI char *php_gcvt(double value, int ndigit, char dec_point, char exponent, c
 			*dst = '\0';
 		} else {
 			/* XXX - optimize */
-			for (sign = decpt, i = 0; (sign /= 10) != 0; i++);
+			int n;
+			for (n = decpt, i = 0; (n /= 10) != 0; i++);
 			dst[i + 1] = '\0';
 			while (decpt != 0) {
 				dst[i--] = '0' + decpt % 10;
@@ -283,8 +285,6 @@ PHPAPI char *php_gcvt(double value, int ndigit, char dec_point, char exponent, c
  */
 /* }}} */
 
-#define FALSE			0
-#define TRUE			1
 #define NUL			'\0'
 #define INT_NULL		((int *)0)
 
@@ -300,23 +300,23 @@ PHPAPI char *php_gcvt(double value, int ndigit, char dec_point, char exponent, c
  * Return value:
  *   - a pointer to a string containing the number (no sign)
  *   - len contains the length of the string
- *   - is_negative is set to TRUE or FALSE depending on the sign
- *     of the number (always set to FALSE if is_unsigned is TRUE)
+ *   - is_negative is set to true or false depending on the sign
+ *     of the number (always set to false if is_unsigned is true)
  *
  * The caller provides a buffer for the string: that is the buf_end argument
  * which is a pointer to the END of the buffer + 1 (i.e. if the buffer
  * is declared as buf[ 100 ], buf_end should be &buf[ 100 ])
  */
 /* char * ap_php_conv_10() {{{ */
-PHPAPI char * ap_php_conv_10(register wide_int num, register bool_int is_unsigned,
-	   register bool_int * is_negative, char *buf_end, register size_t *len)
+PHPAPI char * ap_php_conv_10(register wide_int num, register bool is_unsigned,
+	   register bool * is_negative, char *buf_end, register size_t *len)
 {
 	register char *p = buf_end;
 	register u_wide_int magnitude;
 
 	if (is_unsigned) {
 		magnitude = (u_wide_int) num;
-		*is_negative = FALSE;
+		*is_negative = false;
 	} else {
 		*is_negative = (num < 0);
 
@@ -367,7 +367,7 @@ PHPAPI char * ap_php_conv_10(register wide_int num, register bool_int is_unsigne
  */
 /* PHPAPI char * php_conv_fp() {{{ */
 PHPAPI char * php_conv_fp(register char format, register double num,
-		 boolean_e add_dp, int precision, char dec_point, bool_int * is_negative, char *buf, size_t *len)
+		 boolean_e add_dp, int precision, char dec_point, bool * is_negative, char *buf, size_t *len)
 {
 	register char *s = buf;
 	register char *p, *p_orig;
@@ -389,7 +389,7 @@ PHPAPI char * php_conv_fp(register char format, register double num,
 	if (isalpha((int)*p)) {
 		*len = strlen(p);
 		memcpy(buf, p, *len + 1);
-		*is_negative = FALSE;
+		*is_negative = false;
 		free(p_orig);
 		return (buf);
 	}
@@ -436,12 +436,12 @@ PHPAPI char * php_conv_fp(register char format, register double num,
 	if (format != 'F') {
 		char temp[EXPONENT_LENGTH];		/* for exponent conversion */
 		size_t t_len;
-		bool_int exponent_is_negative;
+		bool exponent_is_negative;
 
 		*s++ = format;			/* either e or E */
 		decimal_point--;
 		if (decimal_point != 0) {
-			p = ap_php_conv_10((wide_int) decimal_point, FALSE, &exponent_is_negative, &temp[EXPONENT_LENGTH], &t_len);
+			p = ap_php_conv_10((wide_int) decimal_point, false, &exponent_is_negative, &temp[EXPONENT_LENGTH], &t_len);
 			*s++ = exponent_is_negative ? '-' : '+';
 
 			/*
@@ -616,7 +616,7 @@ static int format_converter(register buffy * odp, const char *fmt, va_list ap) /
 	boolean_e print_blank;
 	boolean_e adjust_precision;
 	boolean_e adjust_width;
-	bool_int is_negative;
+	bool is_negative;
 
 	sp = odp->nextb;
 	bep = odp->buf_end;
diff --git a/main/snprintf.h b/main/snprintf.h
index b0d824a5ae9..dc476f66ed7 100644
--- a/main/snprintf.h
+++ b/main/snprintf.h
@@ -66,7 +66,7 @@ Example:
 #ifndef SNPRINTF_H
 #define SNPRINTF_H
 
-typedef int bool_int;
+#include <stdbool.h>
 
 typedef enum {
 	NO = 0, YES = 1
@@ -83,7 +83,7 @@ PHPAPI int ap_php_asprintf(char **buf, const char *format, ...) ZEND_ATTRIBUTE_F
 PHPAPI char * php_gcvt(double value, int ndigit, char dec_point, char exponent, char *buf);
 PHPAPI char * php_0cvt(double value, int ndigit, char dec_point, char exponent, char *buf);
 PHPAPI char * php_conv_fp(char format, double num,
-		 boolean_e add_dp, int precision, char dec_point, bool_int * is_negative, char *buf, size_t *len);
+		 boolean_e add_dp, int precision, char dec_point, bool * is_negative, char *buf, size_t *len);
 
 END_EXTERN_C()
 
@@ -141,8 +141,8 @@ typedef enum {
 typedef WIDE_INT wide_int;
 typedef unsigned WIDE_INT u_wide_int;
 
-PHPAPI char * ap_php_conv_10(wide_int num, bool_int is_unsigned,
-	   bool_int * is_negative, char *buf_end, size_t *len);
+PHPAPI char * ap_php_conv_10(wide_int num, bool is_unsigned,
+	   bool * is_negative, char *buf_end, size_t *len);
 
 PHPAPI char * ap_php_conv_p2(u_wide_int num, int nbits,
 		 char format, char *buf_end, size_t *len);
diff --git a/main/spprintf.c b/main/spprintf.c
index ce760569f3a..df8ae5a3402 100644
--- a/main/spprintf.c
+++ b/main/spprintf.c
@@ -95,8 +95,6 @@
 
 #include "snprintf.h"
 
-#define FALSE           0
-#define TRUE            1
 #define NUL             '\0'
 #define INT_NULL        ((int *)0)
 
@@ -220,7 +218,7 @@ static void xbuf_format_converter(void *xbuf, bool is_char, const char *fmt, va_
 	boolean_e print_blank;
 	boolean_e adjust_precision;
 	boolean_e adjust_width;
-	bool_int is_negative;
+	bool is_negative;
 
 	while (*fmt) {
 		if (*fmt != '%') {