diff --git a/scipy/sparse/linalg/isolve/setup.py b/scipy/sparse/linalg/isolve/setup.py
index 7f6815ade..aa5d30df3 100644
--- a/scipy/sparse/linalg/isolve/setup.py
+++ b/scipy/sparse/linalg/isolve/setup.py
@@ -31,6 +31,7 @@ def configuration(parent_package='',top_path=None):
 
     config.add_extension('_iterative',
                          sources=sources,
+                         extra_f77_compile_args=['-O1'],
                          extra_info=lapack_opt)
 
     config.add_data_dir('tests')
