diff --git a/core/modules/jsonapi/src/Controller/FileUpload.php b/core/modules/jsonapi/src/Controller/FileUpload.php
index fb0aa977cd..3974daa0e2 100644
--- a/core/modules/jsonapi/src/Controller/FileUpload.php
+++ b/core/modules/jsonapi/src/Controller/FileUpload.php
@@ -278,8 +278,15 @@ protected function doHandleFileUpload(Request $request, ResourceType $resource_t
     // header. This doesn't change the URI, just the label of the entity.
     $file = $result->getFile();
     if ($file->getFilename() !== $filename) {
-      $file->setFilename($filename);
-      $file->save();
+      // We use explode here instead of pathinfo() because we want everything
+      // after the first ., e.g. for a file example.php.txt we want php.txt not
+      // just txt.
+      [, $original_extension] = @explode('.', $filename, 2);
+      [, $extension] = @explode('.', $file->getFilename(), 2);
+      if ($extension === $original_extension) {
+        $file->setFilename($filename);
+        $file->save();
+      }
     }
     return $file;
   }