diff --git a/scipy/sparse/linalg/isolve/setup.py b/scipy/sparse/linalg/isolve/setup.py
index 829e5f431..396a28037 100644
--- a/scipy/sparse/linalg/isolve/setup.py
+++ b/scipy/sparse/linalg/isolve/setup.py
@@ -38,6 +38,7 @@ def configuration(parent_package='',top_path=None):
     ext = config.add_extension('_iterative',
                                sources=sources,
                                f2py_options=f2py_options,
+                               extra_f77_compile_args=['-O1'],
                                extra_info=lapack_opt)
     ext._pre_build_hook = pre_build_hook
 
