diff --git a/ext/ldap/ldap.c b/ext/ldap/ldap.c
index 14eff31de23..feb3935e24b 100644
--- a/ext/ldap/ldap.c
+++ b/ext/ldap/ldap.c
@@ -2239,6 +2239,11 @@ static void php_ldap_do_modify(INTERNAL_FUNCTION_PARAMETERS, int oper, int ext)
 			RETVAL_FALSE;
 			goto cleanup;
 		}
+		if (ZSTR_LEN(attribute) == 0) {
+			zend_argument_value_error(3, "key must not be empty");
+			RETVAL_FALSE;
+			goto cleanup;
+		}
 		if (zend_str_has_nul_byte(attribute)) {
 			zend_argument_value_error(3, "key must not contain any null bytes");
 			RETVAL_FALSE;
diff --git a/ext/ldap/tests/ldap_add_modify_delete_programming_errors.phpt b/ext/ldap/tests/ldap_add_modify_delete_programming_errors.phpt
index 1d0d21e06de..ae3ec0be52e 100644
--- a/ext/ldap/tests/ldap_add_modify_delete_programming_errors.phpt
+++ b/ext/ldap/tests/ldap_add_modify_delete_programming_errors.phpt
@@ -134,9 +134,7 @@ try {
 --EXPECTF--
 ValueError: ldap_add(): Argument #3 ($entry) must not be empty
 ValueError: ldap_add(): Argument #3 ($entry) must be an associative array of attribute => values
-
-Warning: ldap_add(): Add: Can't contact LDAP server in %s on line %d
-bool(false)
+ValueError: ldap_add(): Argument #3 ($entry) key must not be empty
 ValueError: ldap_add(): Argument #3 ($entry) key must not contain any null bytes
 Error: Object of class stdClass could not be converted to string
 ValueError: ldap_add(): Argument #3 ($entry) list of attribute values must not be empty