diff --git a/ext/json/json_encoder.c b/ext/json/json_encoder.c
index c0fcbe328202a..d56cc24695130 100644
--- a/ext/json/json_encoder.c
+++ b/ext/json/json_encoder.c
@@ -104,7 +104,8 @@ static inline void php_json_encode_double(smart_str *buf, double d, int options)
 
 	php_gcvt(d, (int)PG(serialize_precision), '.', 'e', num);
 	len = strlen(num);
-	if (options & PHP_JSON_PRESERVE_ZERO_FRACTION && strchr(num, '.') == NULL && len < PHP_DOUBLE_MAX_LENGTH - 2) {
+	if ((options & PHP_JSON_PRESERVE_ZERO_FRACTION && strchr(num, '.') == NULL && len < PHP_DOUBLE_MAX_LENGTH - 2)
+	 || (UNEXPECTED(len == 2 && num[0] == '-' && num[1] == '0'))) {
 		num[len++] = '.';
 		num[len++] = '0';
 		num[len] = '\0';
diff --git a/ext/json/tests/bug79908.phpt b/ext/json/tests/bug79908.phpt
new file mode 100644
index 0000000000000..b2aea31069a12
--- /dev/null
+++ b/ext/json/tests/bug79908.phpt
@@ -0,0 +1,12 @@
+--TEST--
+Bug #79908 (json_encode encodes negative zero as int)
+--SKIPIF--
+<?php
+if (!extension_loaded('json')) die("skip json extension not available");
+?>
+--FILE--
+<?php
+var_dump(json_encode(-0.));
+?>
+--EXPECT--
+string(4) "-0.0"