diff --git a/jsbuiltin.c b/jsbuiltin.c
index 8738ddd..1b99b51 100644
--- a/jsbuiltin.c
+++ b/jsbuiltin.c
@@ -43,15 +43,43 @@ static void jsB_parseInt(js_State *J, unsigned int argc)
 {
 	const char *s = js_tostring(J, 1);
 	double radix = js_isdefined(J, 2) ? js_tonumber(J, 2) : 10;
+	char *e;
+	double n;
+
 	while (jsY_iswhite(*s) || jsY_isnewline(*s)) ++s;
-	js_pushnumber(J, strtol(s, NULL, radix == 0 ? 10 : radix));
+	if (radix == 0)
+		radix = 10;
+	if (s[0] == '0' && (s[1] == 'x' || s[1] == 'X')) {
+		s += 2;
+		radix = 16;
+	}
+	n = strtol(s, &e, radix);
+	if (s == e)
+		js_pushnumber(J, NAN);
+	else
+		js_pushnumber(J, n);
 }
 
 static void jsB_parseFloat(js_State *J, unsigned int argc)
 {
 	const char *s = js_tostring(J, 1);
+	char *e;
+	double n;
+
 	while (jsY_iswhite(*s) || jsY_isnewline(*s)) ++s;
-	js_pushnumber(J, strtod(s, NULL));
+	if (!strncmp(s, "Infinity", 8))
+		js_pushnumber(J, INFINITY);
+	else if (!strncmp(s, "+Infinity", 9))
+		js_pushnumber(J, INFINITY);
+	else if (!strncmp(s, "-Infinity", 9))
+		js_pushnumber(J, -INFINITY);
+	else {
+		n = js_strtod(s, &e);
+		if (e == s)
+			js_pushnumber(J, NAN);
+		else
+			js_pushnumber(J, n);
+	}
 }
 
 static void jsB_isNaN(js_State *J, unsigned int argc)
diff --git a/jsvalue.c b/jsvalue.c
index 8ee2600..06de3b8 100644
--- a/jsvalue.c
+++ b/jsvalue.c
@@ -110,6 +110,29 @@ int jsV_toboolean(js_State *J, const js_Value *v)
 	}
 }
 
+double js_strtod(const char *s, char **ep)
+{
+	char *end;
+	double n;
+	const char *e = s;
+	while (*e == '+' || *e == '-') ++e;
+	while (*e >= '0' && *e <= '9') ++e;
+	if (*e == '.') ++e;
+	while (*e >= '0' && *e <= '9') ++e;
+	if (*e == 'e' || *e == 'E') {
+		++e;
+		while (*e == '+' || *e == '-') ++e;
+		while (*e >= '0' && *e <= '9') ++e;
+	}
+	n = strtod(s, &end);
+	if (end == e) {
+		*ep = (char*)e;
+		return n;
+	}
+	*ep = (char*)s;
+	return 0;
+}
+
 /* ToNumber() on a string */
 double jsV_stringtonumber(js_State *J, const char *s)
 {
@@ -118,8 +141,14 @@ double jsV_stringtonumber(js_State *J, const char *s)
 	while (jsY_iswhite(*s) || jsY_isnewline(*s)) ++s;
 	if (s[0] == '0' && s[1] == 'x' && s[2] != 0)
 		n = strtol(s + 2, &e, 16);
+	else if (!strncmp(s, "Infinity", 8))
+		n = INFINITY, e = (char*)s + 8;
+	else if (!strncmp(s, "+Infinity", 9))
+		n = INFINITY, e = (char*)s + 9;
+	else if (!strncmp(s, "-Infinity", 9))
+		n = -INFINITY, e = (char*)s + 9;
 	else
-		n = strtod(s, &e);
+		n = js_strtod(s, &e);
 	while (jsY_iswhite(*e) || jsY_isnewline(*e)) ++e;
 	if (*e) return NAN;
 	return n;
diff --git a/jsvalue.h b/jsvalue.h
index 8cff991..2461d9e 100644
--- a/jsvalue.h
+++ b/jsvalue.h
@@ -123,6 +123,7 @@ const char *jsV_tostring(js_State *J, const js_Value *v);
 js_Object *jsV_toobject(js_State *J, const js_Value *v);
 js_Value jsV_toprimitive(js_State *J, const js_Value *v, int preferred);
 
+double js_strtod(const char *s, char **ep);
 double jsV_numbertointeger(double n);
 int jsV_numbertoint32(double n);
 unsigned int jsV_numbertouint32(double n);