diff --git a/spack.yaml b/spack.yaml
index 63840e9..c07b67a 100644
--- a/spack.yaml
+++ b/spack.yaml
@@ -32,7 +32,7 @@ spack:
         - '@4.6.1'
     parallelio:
       require:
-        - '@2.6.2'
+        - '@2.5.2'
     openmpi:
       require:
         - '@4.1.5'