diff --git a/setup.py b/setup.py
--- a/setup.py
+++ b/setup.py
@@ -455,6 +455,11 @@ class PyBuildExt(build_ext):
             os.unlink(tmpfile)
 
     def detect_modules(self):
+        # On Solaris we prefer to use OpenCSW libraries
+        if host_platform == 'sunos5':
+            add_dir_to_list(self.compiler.library_dirs, '/opt/csw/lib')
+            add_dir_to_list(self.compiler.include_dirs, '/opt/csw/include')
+
         # Ensure that /usr/local is always used, but the local build
         # directories (i.e. '.' and 'Include') must be first.  See issue
         # 10520.