diff --git a/lib/external/externallib.php b/lib/external/externallib.php
index a0526c53379..e0ffd0fcdb6 100644
--- a/lib/external/externallib.php
+++ b/lib/external/externallib.php
@@ -92,7 +92,7 @@ class core_external extends external_api {
                       new external_single_structure(array(
                           'name' => new external_value(PARAM_ALPHANUMEXT, 'param name
                             - if the string expect only one $a parameter then don\'t send this field, just send the value.', VALUE_OPTIONAL),
-                          'value' => new external_value(PARAM_TEXT,'param value'))),
+                          'value' => new external_value(PARAM_RAW,'param value'))),
                           'the definition of a string param (i.e. {$a->name})', VALUE_DEFAULT, array()
                    )
             )
@@ -124,7 +124,7 @@ class core_external extends external_api {
      * @since Moodle 2.4
      */
     public static function get_string_returns() {
-        return new external_value(PARAM_TEXT, 'translated string');
+        return new external_value(PARAM_RAW, 'translated string');
     }
 
     /**
@@ -144,7 +144,7 @@ class core_external extends external_api {
                             new external_single_structure(array(
                                 'name' => new external_value(PARAM_ALPHANUMEXT, 'param name
                                     - if the string expect only one $a parameter then don\'t send this field, just send the value.', VALUE_OPTIONAL),
-                                'value' => new external_value(PARAM_TEXT, 'param value'))),
+                                'value' => new external_value(PARAM_RAW, 'param value'))),
                                 'the definition of a string param (i.e. {$a->name})', VALUE_DEFAULT, array()
                         ))
                     )
@@ -198,7 +198,7 @@ class core_external extends external_api {
                 'stringid' => new external_value(PARAM_STRINGID, 'string id'),
                 'component' => new external_value(PARAM_COMPONENT, 'string component'),
                 'lang' => new external_value(PARAM_LANG, 'lang'),
-                'string' => new external_value(PARAM_TEXT, 'translated string'))
+                'string' => new external_value(PARAM_RAW, 'translated string'))
             ));
     }
 
diff --git a/lib/external/tests/external_test.php b/lib/external/tests/external_test.php
index 85aed00fb95..03415398747 100644
--- a/lib/external/tests/external_test.php
+++ b/lib/external/tests/external_test.php
@@ -78,6 +78,26 @@ class core_external_testcase extends externallib_advanced_testcase {
                       array('name' => 'id', 'value' => $service->id)));
     }
 
+    /**
+     * Test get_string with HTML.
+     */
+    public function test_get_string_containing_html() {
+        $result = core_external::get_string('registrationinfo');
+        $actual = external_api::clean_returnvalue(core_external::get_string_returns(), $result);
+        $expected = get_string('registrationinfo', 'moodle');
+        $this->assertSame($expected, $actual);
+    }
+
+    /**
+     * Test get_string with arguments containing HTML.
+     */
+    public function test_get_string_with_args_containing_html() {
+        $result = core_external::get_string('added', 'moodle', null, [['value' => '<strong>Test</strong>']]);
+        $actual = external_api::clean_returnvalue(core_external::get_string_returns(), $result);
+        $expected = get_string('added', 'moodle', '<strong>Test</strong>');
+        $this->assertSame($expected, $actual);
+    }
+
     /**
      * Test get_strings
      */
@@ -114,6 +134,29 @@ class core_external_testcase extends externallib_advanced_testcase {
         }
     }
 
+    /**
+     * Test get_strings with HTML.
+     */
+    public function test_get_strings_containing_html() {
+        $result = core_external::get_strings([['stringid' => 'registrationinfo'], ['stringid' => 'loginaspasswordexplain']]);
+        $actual = external_api::clean_returnvalue(core_external::get_strings_returns(), $result);
+        $this->assertSame(get_string('registrationinfo', 'moodle'), $actual[0]['string']);
+        $this->assertSame(get_string('loginaspasswordexplain', 'moodle'), $actual[1]['string']);
+    }
+
+    /**
+     * Test get_strings with arguments containing HTML.
+     */
+    public function test_get_strings_with_args_containing_html() {
+        $result = core_external::get_strings([
+            ['stringid' => 'added', 'stringparams' => [['value' => '<strong>Test</strong>']]],
+            ['stringid' => 'loggedinas', 'stringparams' => [['value' => '<strong>Test</strong>']]]]
+        );
+        $actual = external_api::clean_returnvalue(core_external::get_strings_returns(), $result);
+        $this->assertSame(get_string('added', 'moodle', '<strong>Test</strong>'), $actual[0]['string']);
+        $this->assertSame(get_string('loggedinas', 'moodle', '<strong>Test</strong>'), $actual[1]['string']);
+    }
+
     /**
      * Test get_component_strings
      */