diff --git a/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageDelete.php b/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageDelete.php
index ff9e5f5ffebaa08e2b1fe5230f8bca7707960fcd..b8d2a0c132d7488852a817a23295cea58da9e1b6 100755
--- a/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageDelete.php
+++ b/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageDelete.php
@@ -11,7 +11,7 @@ use Psr\Http\Message\ServerRequestInterface as Request;
 
 class StructuralElementsImageDelete extends NonJsonApiController
 {
-    public function invoke(Request $request, Response $response, array $args)
+    public function invoke(Request $request, Response $response, array $args): Response
     {
         if (!($structuralElement = StructuralElement::find($args['id']))) {
             throw new RecordNotFoundException();
diff --git a/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageUpload.php b/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageUpload.php
index d594d752b4e06ad3c20750c4b43481732e278f0e..070ca6c842c287bb9416066c352520a4d7f6a358 100755
--- a/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageUpload.php
+++ b/lib/classes/JsonApi/Routes/Courseware/StructuralElementsImageUpload.php
@@ -17,7 +17,7 @@ class StructuralElementsImageUpload extends NonJsonApiController
 {
     use CoursewareInstancesHelper, FilesRoutesHelper;
 
-    public function invoke(Request $request, Response $response, array $args)
+    public function invoke(Request $request, Response $response, array $args): Response
     {
         if (!($structuralElement = StructuralElement::find($args['id']))) {
             throw new RecordNotFoundException();
diff --git a/lib/classes/JsonApi/Routes/Files/FileRefsContentShow.php b/lib/classes/JsonApi/Routes/Files/FileRefsContentShow.php
index 5b470c5ebb6ff438a05df02a27addea0adba8688..b2b67ce024620ccf9afddef40c49527ebac9d667 100644
--- a/lib/classes/JsonApi/Routes/Files/FileRefsContentShow.php
+++ b/lib/classes/JsonApi/Routes/Files/FileRefsContentShow.php
@@ -14,7 +14,7 @@ class FileRefsContentShow extends NonJsonApiController
 {
     use EtagHelperTrait;
 
-    public function invoke(Request $request, Response $response, array $args)
+    public function invoke(Request $request, Response $response, array $args): Response
     {
         if (!$fileRef = \FileRef::find($args['id'])) {
             throw new RecordNotFoundException();
diff --git a/lib/classes/JsonApi/Routes/Files/FileRefsContentUpdate.php b/lib/classes/JsonApi/Routes/Files/FileRefsContentUpdate.php
index 30c7325d791b137ba964b18fb612f00aaf068438..c1066a859e80508235c43f5bc17c4640f11ebbbb 100644
--- a/lib/classes/JsonApi/Routes/Files/FileRefsContentUpdate.php
+++ b/lib/classes/JsonApi/Routes/Files/FileRefsContentUpdate.php
@@ -13,7 +13,7 @@ class FileRefsContentUpdate extends NonJsonApiController
 {
     use RoutesHelperTrait;
 
-    public function invoke(Request $request, Response $response, array $args)
+    public function invoke(Request $request, Response $response, array $args): Response
     {
         if (!$fileRef = \FileRef::find($args['id'])) {
             throw new RecordNotFoundException();