diff --git a/var/spack/repos/builtin/packages/py-grpcio/package.py b/var/spack/repos/builtin/packages/py-grpcio/package.py
index 56826c8fb6c..b53cb4a0f17 100644
--- a/var/spack/repos/builtin/packages/py-grpcio/package.py
+++ b/var/spack/repos/builtin/packages/py-grpcio/package.py
@@ -32,6 +32,8 @@ def setup_build_environment(self, env):
         env.set('GRPC_PYTHON_BUILD_SYSTEM_OPENSSL', True)
         env.set('GRPC_PYTHON_BUILD_SYSTEM_ZLIB', True)
         env.set('GRPC_PYTHON_BUILD_SYSTEM_CARES', True)
+        # https://github.com/grpc/grpc/pull/24449
+        env.set('GRPC_BUILD_WITH_BORING_SSL_ASM', '')
 
         for dep in self.spec.dependencies(deptype='link'):
             query = self.spec[dep.name]