diff --git a/repos/spack_repo/builtin/packages/osg_ca_certs/package.py b/repos/spack_repo/builtin/packages/osg_ca_certs/package.py
index 59c54078c88..5104a8e9df8 100644
--- a/repos/spack_repo/builtin/packages/osg_ca_certs/package.py
+++ b/repos/spack_repo/builtin/packages/osg_ca_certs/package.py
@@ -56,9 +56,9 @@ class OsgCaCerts(Package):
     depends_on("openssl")
 
     def setup_build_environment(self, env: EnvironmentModifications) -> None:
-        env.set("OSG_CERTS_VERSION", self.version[:2])
+        env.set("OSG_CERTS_VERSION", str(self.version[:2]))
         env.set("OUR_CERTS_VERSION", str(self.version[:2]) + "NEW")
-        env.set("IGTF_CERTS_VERSION", self.version[3:])
+        env.set("IGTF_CERTS_VERSION", str(self.version[3:]))
         env.set("CADIST", join_path(self.stage.source_path, "certificates"))
         env.set("PKG_NAME", self.spec.name)