The test for iconv_incs tested explicitly for None, but [] is returned
if the include files cannot be found.
diff --git a/setup.py b/setup.py
index 31df74c..96ed416 100644
--- a/setup.py
+++ b/setup.py
@@ -622,8 +622,8 @@
             iconv_libs = find_library_file(self.compiler, 'iconv', lib_dirs,
                                            ['/usr/local/lib', '/usr/pkg/lib'])
 
-            if (iconv_incs is not None):
-                if iconv_libs is not None:
+            if iconv_incs:
+                if iconv_libs:
                     iconv_libraries = ['iconv']
                 else:
                     iconv_libraries = [] # in libc