diff --git a/var/spack/repos/builtin/packages/esmf/package.py b/var/spack/repos/builtin/packages/esmf/package.py
index c7c9b4bb03..885ca3817e 100644
--- a/var/spack/repos/builtin/packages/esmf/package.py
+++ b/var/spack/repos/builtin/packages/esmf/package.py
@@ -24,6 +24,7 @@ class Esmf(MakefilePackage):
     # Develop is a special name for spack and is always considered the newest version
     version("develop", branch="develop")
     # generate chksum with spack checksum esmf@x.y.z
+    version("8.4.0", sha256="28531810bf1ae78646cda6494a53d455d194400f19dccd13d6361871de42ed0f")
     version(
         "8.3.1",
         sha256="6c39261e55dcdf9781cdfa344417b9606f7f961889d5ec626150f992f04f146d",
@@ -245,7 +246,8 @@ def edit(self, spec, prefix):
         #######
 
         # ESMF_OS must be set for Cray systems
-        if "platform=cray" in self.spec:
+        # But spack no longer gives arch == cray
+        if self.compiler.name == "cce" or "^cray-mpich" in self.spec:
             os.environ["ESMF_OS"] = "Unicos"
 
         #######
@@ -326,7 +328,7 @@ def edit(self, spec, prefix):
         ##############
         # ParallelIO #
         ##############
-        if "+parallelio" in spec and "+mpi" in spec:
+        if "+parallelio" in spec:
             os.environ["ESMF_PIO"] = "external"
             os.environ["ESMF_PIO_LIBPATH"] = spec["parallelio"].prefix.lib
             os.environ["ESMF_PIO_INCLUDE"] = spec["parallelio"].prefix.include