diff --git a/litex/build/generic_platform.py b/litex/build/generic_platform.py
index fcbb87f7c..4e9101b51 100644
--- a/litex/build/generic_platform.py
+++ b/litex/build/generic_platform.py
@@ -368,6 +368,7 @@ class GenericPlatform:
                 pass
 
     def add_source(self, filename, language=None, library=None):
+        filename = os.path.abspath(filename)
         if language is None:
             language = tools.language_by_filename(filename)
         if library is None:
@@ -375,7 +376,7 @@ class GenericPlatform:
         for f, _, _ in self.sources:
             if f == filename:
                 return
-        self.sources.append((os.path.abspath(filename), language, library))
+        self.sources.append((filename, language, library))
 
     def add_sources(self, path, *filenames, language=None, library=None):
         for f in filenames: