diff --git a/thumbnailer/CMakeLists.txt b/thumbnailer/CMakeLists.txt
index e91a96d..fda0537 100644
--- a/thumbnailer/CMakeLists.txt
+++ b/thumbnailer/CMakeLists.txt
@@ -9,6 +9,7 @@ if(BUILD_THUMBNAILER)
             ../rawimage.h
             ../rawimage.cpp
             ../rawimage_sse.cpp)
+        set_target_properties(tenmonthumbnailer PROPERTIES PREFIX "")
 
         target_compile_definitions(tenmonthumbnailer PRIVATE NO_QT)
         target_include_directories(tenmonthumbnailer PRIVATE ../libXISF)
diff --git a/thumbnailer/Dll.cpp b/thumbnailer/Dll.cpp
index 57f1619..356fb90 100644
--- a/thumbnailer/Dll.cpp
+++ b/thumbnailer/Dll.cpp
@@ -226,6 +226,8 @@ STDAPI DllUnregisterServer()
     {
         L"Software\\Classes\\CLSID\\" SZ_CLSID_TENMONTHUMBHANDLER,
         L"Software\\Classes\\.xisf\\ShellEx\\{e357fccd-a995-4576-b01f-234630154e96}"
+        L"Software\\Classes\\.fits\\ShellEx\\{e357fccd-a995-4576-b01f-234630154e96}"
+        L"Software\\Classes\\.fit\\ShellEx\\{e357fccd-a995-4576-b01f-234630154e96}"
     };
 
     // Delete the registry entries