diff --git a/ext/standard/string.c b/ext/standard/string.c
index 622ed3a9d43..881e172c6c2 100644
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -5059,6 +5059,7 @@ PHP_FUNCTION(str_repeat)
 	/* Initialize the result string */
 	result = zend_string_safe_alloc(ZSTR_LEN(input_str), mult, 0, 0);
 	result_len = ZSTR_LEN(input_str) * mult;
+	ZSTR_COPY_CONCAT_PROPERTIES(result, input_str);
 
 	/* Heavy optimization for situations where input string is 1 byte long */
 	if (ZSTR_LEN(input_str) == 1) {
diff --git a/ext/zend_test/tests/strings_marked_as_utf8.phpt b/ext/zend_test/tests/strings_marked_as_utf8.phpt
index 5b6dfb6a076..1519459f1da 100644
--- a/ext/zend_test/tests/strings_marked_as_utf8.phpt
+++ b/ext/zend_test/tests/strings_marked_as_utf8.phpt
@@ -107,6 +107,14 @@ $s = $o . $o;
 var_dump($s);
 var_dump(zend_test_is_string_marked_as_valid_utf8($s));
 
+echo "str_repeat:\n";
+$string = "a";
+$string_concat = str_repeat($string, 100);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+$string = "\xff";
+$string_concat = str_repeat($string, 100);
+var_dump(zend_test_is_string_marked_as_valid_utf8($string_concat));
+
 ?>
 --EXPECT--
 Empty strings:
@@ -148,3 +156,6 @@ bool(true)
 Concatenation of objects:
 string(2) "zz"
 bool(true)
+str_repeat:
+bool(true)
+bool(false)