1diff --git a/rpy2/rinterface_lib/embedded.py b/rpy2/rinterface_lib/embedded.py
2index 1f4babbf..322363c5 100644
3--- a/rpy2/rinterface_lib/embedded.py
4+++ b/rpy2/rinterface_lib/embedded.py
5@@ -118,6 +118,16 @@ def _initr(
6 if openrlib.R_HOME is None:
7 raise ValueError('openrlib.R_HOME cannot be None.')
8 os.environ['R_HOME'] = openrlib.R_HOME
9+
10+ # path to libraries
11+ existing = os.environ.get('R_LIBS_SITE')
12+ if existing is not None:
13+ prefix = existing + ':'
14+ else:
15+ prefix = ''
16+ additional = '@NIX_R_LIBS_SITE@'
17+ os.environ['R_LIBS_SITE'] = prefix + additional
18+
19 options_c = [ffi.new('char[]', o.encode('ASCII')) for o in _options]
20 n_options = len(options_c)
21 n_options_c = ffi.cast('int', n_options)