diff --git a/var/spack/repos/builtin/packages/mpich/package.py b/var/spack/repos/builtin/packages/mpich/package.py
index b4d132fe73e..4d6e9699e7f 100644
--- a/var/spack/repos/builtin/packages/mpich/package.py
+++ b/var/spack/repos/builtin/packages/mpich/package.py
@@ -311,6 +311,8 @@ def setup_build_environment(self, env):
         # Same fix but for macOS - avoids issue #17934
         if self.spec.satisfies('%apple-clang@11:'):
             env.set('FFLAGS', '-fallow-argument-mismatch')
+        if self.spec.satisfies('%clang@11:'):
+            env.set('FFLAGS', '-fallow-argument-mismatch')
 
     def setup_run_environment(self, env):
         # Because MPI implementations provide compilers, they have to add to