diff --git a/Modules/Core/src/IO/mitkCustomMimeType.cpp b/Modules/Core/src/IO/mitkCustomMimeType.cpp
index 95d96c5..832d114 100644
--- a/Modules/Core/src/IO/mitkCustomMimeType.cpp
+++ b/Modules/Core/src/IO/mitkCustomMimeType.cpp
@@ -152,8 +152,8 @@ bool CustomMimeType::ParsePathForExtension(const std::string& path, std::string&
   {
     if (!iter->empty() && path.size() >= iter->size())
     {
-      FindCaseInsensitive cmp(*iter);
-      if (cmp(path.substr(path.size() - iter->size())))
+      FindCaseInsensitive cmp("."+*iter);
+      if (cmp(path.substr(path.size() - iter->size() - 1)))
       {
         extension = "." + *iter;
         std::string filenameWithExtension = itksys::SystemTools::GetFilenameName(path);