diff --git a/ext/standard/basic_functions.stub.php b/ext/standard/basic_functions.stub.php
index e27dca069c55b..fb1e6277b73ab 100644
--- a/ext/standard/basic_functions.stub.php
+++ b/ext/standard/basic_functions.stub.php
@@ -2310,16 +2310,16 @@ function strcoll(string $string1, string $string2): int {}
  * @frameless-function {"arity": 1}
  * @frameless-function {"arity": 2}
  */
-function trim(string $string, string $characters = " \n\r\t\v\0"): string {}
+function trim(string $string, string $characters = " \f\n\r\t\v\0"): string {}
 
 /** @compile-time-eval */
-function rtrim(string $string, string $characters = " \n\r\t\v\0"): string {}
+function rtrim(string $string, string $characters = " \f\n\r\t\v\0"): string {}
 
 /** @alias rtrim */
-function chop(string $string, string $characters = " \n\r\t\v\0"): string {}
+function chop(string $string, string $characters = " \f\n\r\t\v\0"): string {}
 
 /** @compile-time-eval */
-function ltrim(string $string, string $characters = " \n\r\t\v\0"): string {}
+function ltrim(string $string, string $characters = " \f\n\r\t\v\0"): string {}
 
 /**
  * @compile-time-eval
diff --git a/ext/standard/string.c b/ext/standard/string.c
index 0b7d5be1a2576..3455379f0f468 100644
--- a/ext/standard/string.c
+++ b/ext/standard/string.c
@@ -519,7 +519,7 @@ static inline zend_result php_charmask(const unsigned char *input, size_t len, c
  * mode 1 : trim left
  * mode 2 : trim right
  * mode 3 : trim left and right
- * what indicates which chars are to be trimmed. NULL->default (' \t\n\r\v\0')
+ * what indicates which chars are to be trimmed. NULL->default (' \f\t\n\r\v\0')
  */
 static zend_always_inline zend_string *php_trim_int(zend_string *str, const char *what, size_t what_len, int mode)
 {
@@ -576,7 +576,7 @@ static zend_always_inline zend_string *php_trim_int(zend_string *str, const char
 				unsigned char c = (unsigned char)*start;
 
 				if (c <= ' ' &&
-				    (c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\v' || c == '\0')) {
+				    (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v' || c == '\0')) {
 					start++;
 				} else {
 					break;
@@ -588,7 +588,7 @@ static zend_always_inline zend_string *php_trim_int(zend_string *str, const char
 				unsigned char c = (unsigned char)*(end-1);
 
 				if (c <= ' ' &&
-				    (c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == '\v' || c == '\0')) {
+				    (c == ' ' || c == '\f' || c == '\n' || c == '\r' || c == '\t' || c == '\v' || c == '\0')) {
 					end--;
 				} else {
 					break;
@@ -611,7 +611,7 @@ static zend_always_inline zend_string *php_trim_int(zend_string *str, const char
  * mode 1 : trim left
  * mode 2 : trim right
  * mode 3 : trim left and right
- * what indicates which chars are to be trimmed. NULL->default (' \t\n\r\v\0')
+ * what indicates which chars are to be trimmed. NULL->default (' \f\t\n\r\v\0')
  */
 PHPAPI zend_string *php_trim(zend_string *str, const char *what, size_t what_len, int mode)
 {
diff --git a/tests/classes/tostring_001.phpt b/tests/classes/tostring_001.phpt
index e9ef7b4175832..ffbd7692727de 100644
--- a/tests/classes/tostring_001.phpt
+++ b/tests/classes/tostring_001.phpt
@@ -12,7 +12,7 @@ class test2
     function __toString()
     {
         echo __METHOD__ . "()\n";
-        return "Converted\n";
+        return "\fConverted\n";
     }
 }