diff --git a/rpy2/rinterface_lib/embedded.py b/rpy2/rinterface_lib/embedded.py
index cc32b6d..3969ad0 100644
--- a/rpy2/rinterface_lib/embedded.py
+++ b/rpy2/rinterface_lib/embedded.py
@@ -113,6 +113,16 @@ def _initr(interactive: bool = True,
         if isinitialized():
             return None
         os.environ['R_HOME'] = openrlib.R_HOME
+
+        # path to libraries
+        existing = os.environ.get('R_LIBS_SITE')
+        if existing is not None:
+            prefix = existing + ':'
+        else:
+            prefix = ''
+        additional = '@NIX_R_LIBS_SITE@'
+        os.environ['R_LIBS_SITE'] = prefix + additional
+
         options_c = [ffi.new('char[]', o.encode('ASCII')) for o in _options]
         n_options = len(options_c)
         n_options_c = ffi.cast('int', n_options)