diff --git a/packages/mom5/package.py b/packages/mom5/package.py
index 16d72e7..0408bae 100644
--- a/packages/mom5/package.py
+++ b/packages/mom5/package.py
@@ -498,7 +498,7 @@ def build(self, spec, prefix):
                 build.add_default_env("REPRO", "true")
 
             if self.spec.satisfies("+access-gtracers"):
-                build.add_default_env("SPACK_FMS_EXTERNAL", "true")
+                build.add_default_env("SPACK_GTRACERS_EXTERNAL", "true")
 
             if not self.spec.satisfies("@access-esm1.5"):
                 # The MOM5 commit d7ba13a3f364ce130b6ad0ba813f01832cada7a2