diff --git a/sklearn/manifold/setup.py b/sklearn/manifold/setup.py
index 0db2d5d..fb4fc38 100644
--- a/sklearn/manifold/setup.py
+++ b/sklearn/manifold/setup.py
@@ -15,14 +15,14 @@ def configuration(parent_package="", top_path=None):
     config.add_extension("_utils",
                          sources=["_utils.pyx"],
                          include_dirs=[numpy.get_include()],
-                         libraries=libraries,
-                         extra_compile_args=["-O3"])
+                         libraries=libraries)
+
 
     config.add_extension("_barnes_hut_tsne",
                          sources=["_barnes_hut_tsne.pyx"],
                          include_dirs=[numpy.get_include()],
-                         libraries=libraries,
-                         extra_compile_args=['-O3'])
+                         libraries=libraries)
+
 
     config.add_subpackage('tests')
 
diff --git a/sklearn/tree/setup.py b/sklearn/tree/setup.py
index 079ae9d..b38ee4b 100644
--- a/sklearn/tree/setup.py
+++ b/sklearn/tree/setup.py
@@ -12,23 +12,19 @@ def configuration(parent_package="", top_path=None):
     config.add_extension("_tree",
                          sources=["_tree.pyx"],
                          include_dirs=[numpy.get_include()],
-                         libraries=libraries,
-                         extra_compile_args=["-O3"])
+                         libraries=libraries)
     config.add_extension("_splitter",
                          sources=["_splitter.pyx"],
                          include_dirs=[numpy.get_include()],
-                         libraries=libraries,
-                         extra_compile_args=["-O3"])
+                         libraries=libraries)
     config.add_extension("_criterion",
                          sources=["_criterion.pyx"],
                          include_dirs=[numpy.get_include()],
-                         libraries=libraries,
-                         extra_compile_args=["-O3"])
+                         libraries=libraries)
     config.add_extension("_utils",
                          sources=["_utils.pyx"],
                          include_dirs=[numpy.get_include()],
-                         libraries=libraries,
-                         extra_compile_args=["-O3"])
+                         libraries=libraries)
 
     config.add_subpackage("tests")