diff --git a/var/spack/repos/builtin/packages/mpich/package.py b/var/spack/repos/builtin/packages/mpich/package.py
index 8a7d32b525..e736634c5a 100644
--- a/var/spack/repos/builtin/packages/mpich/package.py
+++ b/var/spack/repos/builtin/packages/mpich/package.py
@@ -330,11 +330,14 @@ def setup_build_environment(self, env):
         # https://bugzilla.redhat.com/show_bug.cgi?id=1795817
         if self.spec.satisfies('%gcc@10:'):
             env.set('FFLAGS', '-fallow-argument-mismatch')
+            env.set('FCFLAGS', '-fallow-argument-mismatch')
         # Same fix but for macOS - avoids issue #17934
         if self.spec.satisfies('%apple-clang@11:'):
             env.set('FFLAGS', '-fallow-argument-mismatch')
+            env.set('FCFLAGS', '-fallow-argument-mismatch')
         if self.spec.satisfies('%clang@11:'):
             env.set('FFLAGS', '-fallow-argument-mismatch')
+            env.set('FCFLAGS', '-fallow-argument-mismatch')
 
         if 'pmi=cray' in self.spec:
             env.set(