diff --git a/NEWS b/NEWS
index 2c65e9799aba..e5a758fc34f8 100644
--- a/NEWS
+++ b/NEWS
@@ -5,6 +5,9 @@ PHP                                                                        NEWS
 - Core:
   . Exiting a namespace now clears seen symbols. (ilutov)
 
+- Standard:
+  . php_uname() now throws ValueErrors on invalid inputs. (Girgias)
+
 15 Aug 2024, PHP 8.4.0beta1
 
 - Core:
diff --git a/UPGRADING b/UPGRADING
index bcf95365538b..350441c51c6e 100644
--- a/UPGRADING
+++ b/UPGRADING
@@ -193,6 +193,7 @@ PHP 8.4 UPGRADE NOTES
     $enclosure arguments are not one byte long, or if the $escape is not one
     byte long or the empty string. This aligns the behaviour to be identical
     to that of fputcsv() and fgetcsv().
+  . php_uname() now throws ValueErrors on invalid inputs.
 
 - Tidy:
   . Failures in the constructor now throw exceptions rather than emitting
diff --git a/ext/standard/info.c b/ext/standard/info.c
index 5e273588cb17..2da58f3cccef 100644
--- a/ext/standard/info.c
+++ b/ext/standard/info.c
@@ -656,10 +656,16 @@ static void php_get_windows_cpu(char *buf, size_t bufsize)
 /* }}}  */
 #endif
 
+static inline bool php_is_valid_uname_mode(char mode) {
+	return mode == 'a' || mode == 'm' || mode == 'n' || mode == 'r' || mode == 's' || mode == 'v';
+}
+
 /* {{{ php_get_uname */
 PHPAPI zend_string *php_get_uname(char mode)
 {
 	char *php_uname;
+
+	ZEND_ASSERT(php_is_valid_uname_mode(mode));
 #ifdef PHP_WIN32
 	char tmp_uname[256];
 	DWORD dwBuild=0;
@@ -1313,15 +1319,26 @@ PHP_FUNCTION(php_sapi_name)
 /* {{{ Return information about the system PHP was built on */
 PHP_FUNCTION(php_uname)
 {
-	char *mode = "a";
+	char *mode_str = "a";
 	size_t modelen = sizeof("a")-1;
 
 	ZEND_PARSE_PARAMETERS_START(0, 1)
 		Z_PARAM_OPTIONAL
-		Z_PARAM_STRING(mode, modelen)
+		Z_PARAM_STRING(mode_str, modelen)
 	ZEND_PARSE_PARAMETERS_END();
 
-	RETURN_STR(php_get_uname(*mode));
+	if (modelen != 1) {
+		zend_argument_value_error(1, "must be a single character");
+		RETURN_THROWS();
+	}
+
+	char mode = *mode_str;
+	if (!php_is_valid_uname_mode(mode)) {
+		zend_argument_value_error(1, "must be one of \"a\", \"m\", \"n\", \"r\", \"s\", or \"v\"");
+		RETURN_THROWS();
+	}
+
+	RETURN_STR(php_get_uname(mode));
 }
 
 /* }}} */
diff --git a/ext/standard/tests/general_functions/php_uname_error.phpt b/ext/standard/tests/general_functions/php_uname_error.phpt
index 2f65ed587d36..694ec19fb6b3 100644
--- a/ext/standard/tests/general_functions/php_uname_error.phpt
+++ b/ext/standard/tests/general_functions/php_uname_error.phpt
@@ -1,17 +1,26 @@
 --TEST--
-Test php_uname() function -  error conditions - pass function incorrect arguments
+php_uname(): Invalid arguments
 --FILE--
 <?php
 
-echo "*** Testing php_uname() - error test\n";
-
-echo "\n-- Testing php_uname() function with invalid mode --\n";
-// am invalid mode should result in same o/p as mode 'a'
-var_dump( php_uname('z') == php_uname('z') );
+try {
+    var_dump(php_uname(''));
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+try {
+    var_dump(php_uname('test'));
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
+try {
+    var_dump(php_uname('z'));
+} catch (Throwable $e) {
+    echo $e::class, ': ', $e->getMessage(), PHP_EOL;
+}
 
 ?>
 --EXPECT--
-*** Testing php_uname() - error test
-
--- Testing php_uname() function with invalid mode --
-bool(true)
+ValueError: php_uname(): Argument #1 ($mode) must be a single character
+ValueError: php_uname(): Argument #1 ($mode) must be a single character
+ValueError: php_uname(): Argument #1 ($mode) must be one of "a", "m", "n", "r", "s", or "v"