diff --git a/setup.py b/setup.py
index fe47797..1cd1503 100644
--- a/setup.py
+++ b/setup.py
@@ -1503,6 +1503,9 @@
             expat_inc = [os.path.join(os.getcwd(), srcdir, 'Modules', 'expat')]
             define_macros = [
                 ('HAVE_EXPAT_CONFIG_H', '1'),
+                # bpo-30947: Python uses best available entropy sources to
+                # call XML_SetHashSalt(), expat entropy sources are not needed
+                ('XML_POOR_ENTROPY', '1'),
             ]
             expat_lib = []
             expat_sources = ['expat/xmlparse.c',