diff --git a/lib/arduino_ci/cpp_library.rb b/lib/arduino_ci/cpp_library.rb
index 2d481f1b..0d3fe0f9 100644
--- a/lib/arduino_ci/cpp_library.rb
+++ b/lib/arduino_ci/cpp_library.rb
@@ -164,10 +164,7 @@ def exclude_dirs=(rval)
     # but we rely on the cli to decide for us
     # @return [bool]
     def one_point_five?
-      return false unless library_properties?
-
-      src_dir = path + "src"
-      src_dir.exist? && src_dir.directory?
+      !info["library"]["is_legacy"]
     end
 
     # Guess whether a file is part of the vendor bundle (indicating we should ignore it).