diff --git a/main/snprintf.c b/main/snprintf.c
index c019d1a2fa0..fb9f08b6772 100644
--- a/main/snprintf.c
+++ b/main/snprintf.c
@@ -139,7 +139,7 @@ PHPAPI char *php_gcvt(double value, int ndigit, char dec_point, char exponent, c
 		 * Infinity or NaN, convert to inf or nan with sign.
 		 * We assume the buffer is at least ndigit long.
 		 */
-		snprintf(buf, ndigit + 1, "%s%s", sign ? "-" : "",
+		snprintf(buf, ndigit + 1, "%s%s", (sign && *digits == 'I') ? "-" : "",
 				*digits == 'I' ? "INF" : "NAN");
 		zend_freedtoa(digits);
 		return (buf);