diff --git a/tdesu/CMakeLists.txt b/tdesu/CMakeLists.txt
index 1db531b46..4c33fb0d8 100644
--- a/tdesu/CMakeLists.txt
+++ b/tdesu/CMakeLists.txt
@@ -48,6 +48,10 @@ if( WITH_SUDO_TDESU_BACKEND )
 else()
   set( DEFAULT_SUPER_USER_COMMAND su CACHE INTERNAL "" FORCE )
 endif()
+find_file( TDESU_BACKEND ${DEFAULT_SUPER_USER_COMMAND} PATHS ENV PATH )
+if( TDESU_BACKEND-NOTFOUND )
+  tde_message_fatal( "${DEFAULT_SUPER_USER_COMMAND} was chosen as tdesu backend, but was not found in path." )
+endif( TDESU_BACKEND-NOTFOUND )
 
 add_subdirectory( tdesu )
 add_subdirectory( tdesud )