diff --git a/infra/gcb/build_lib.py b/infra/gcb/build_lib.py
index 0fe22bbd9..2c1e71b0c 100644
--- a/infra/gcb/build_lib.py
+++ b/infra/gcb/build_lib.py
@@ -184,6 +184,7 @@ def project_image_steps(name, image, language):
           '.',
       ],
       'dir': 'oss-fuzz/projects/' + name,
+      'env': ['FUZZING_LANGUAGE=%s' % language],
   }, {
       'name':
           image,