diff --git a/targets/gcc_64.yml b/targets/gcc_64.yml
index 44f8c17..7a725cb 100644
--- a/targets/gcc_64.yml
+++ b/targets/gcc_64.yml
@@ -28,6 +28,7 @@ compiler:
     prefix: '-D'
     items:
       - 'UNITY_SUPPORT_64'
+      - 'UNITY_POINTER_WIDTH=64'
   object_files:
     prefix: '-o'
     extension: '.o'