diff --git a/CTestCustom.cmake b/CTestCustom.cmake
index 5c809ea63f322ae0a15f99f7e530fa9eadc10580..7bfd31ced481d61ae2eb347a21443bbdac1e1e88 100644
--- a/CTestCustom.cmake
+++ b/CTestCustom.cmake
@@ -86,7 +86,7 @@ Set (CTEST_CUSTOM_COVERAGE_EXCLUDE
      ".*Dict.cxx"
      ".*Fair.*"
      ".*GTest.*"
-     "external/"
+     ".*external/.*"
     )
 
 Set(CTEST_CUSTOM_ERROR_EXCEPTION