diff --git a/additional_recipes/ros2-distro-mutex/recipe.yaml b/additional_recipes/ros2-distro-mutex/recipe.yaml
index a9ec5b0cd..4d7fcb2d7 100644
--- a/additional_recipes/ros2-distro-mutex/recipe.yaml
+++ b/additional_recipes/ros2-distro-mutex/recipe.yaml
@@ -6,7 +6,7 @@ build:
   number: 0
   # Note: keep in sync with build number
   # Cannot be done automatically, see https://github.com/mamba-org/boa/issues/278
-  string: humble
+  string: humble_0
   run_exports:
     weak:
       - "{{ pin_subpackage('ros2-distro-mutex', max_pin='x.x') }}"