Index: setup.py
===================================================================
--- setup.py	(revision 4187)
+++ setup.py	(working copy)
@@ -87,7 +87,7 @@
     X11 = ['/usr/X11'] * (not options.osx_frameworks)
 
     if sys.platform == 'darwin':
-        for prefix in ['/sw', '/opt/local', '/usr/local']:
+        for prefix in ['@PREFIX@', '/usr/local']:
             if sys.executable.startswith(prefix):
                 return [prefix] + X11
 
@@ -392,12 +392,12 @@
     libs += ["GLEW"]
     libs += pyogl_libs
 
-    ext_comp_args += ["-ffast-math", "-funroll-loops", "-fcommon"]
+    ext_comp_args += ["-ffast-math", "-funroll-loops", "-fcommon", "-O3"]
 
     # optimization currently causes a clang segfault on OS X 10.9 when
     # compiling layer2/RepCylBond.cpp
-    if sys.platform != 'darwin':
-        ext_comp_args += ["-O3"]
+    if sys.platform == 'darwin':
+        ext_comp_args += ["-fno-strict-aliasing"]
 
 def get_pymol_version():
     return re.findall(r'_PyMOL_VERSION "(.*)"', open('layer0/Version.h').read())[0]