diff --git a/virtualenv.py b/virtualenv.py
index 1d46506..68284f6 100755
--- a/virtualenv.py
+++ b/virtualenv.py
@@ -860,7 +860,10 @@ def install_wheel(project_names, py_executable, search_dirs=None,
 
         import pip
 
-        cert_data = pkgutil.get_data("pip._vendor.requests", "cacert.pem")
+        try:
+            cert_data = pkgutil.get_data("pip._vendor.requests", "cacert.pem")
+        except IOError:
+            cert_data = None
         if cert_data is not None:
             cert_file = tempfile.NamedTemporaryFile(delete=False)
             cert_file.write(cert_data)