diff --git a/dotbot/cli.py b/dotbot/cli.py
index dc90909..c0e4365 100644
--- a/dotbot/cli.py
+++ b/dotbot/cli.py
@@ -1,3 +1,5 @@
+import os
+import socket
 from argparse import ArgumentParser
 from .config import ConfigReader, ReadingError
 from .dispatcher import Dispatcher, DispatchError
@@ -24,6 +26,8 @@ def read_config(config_file):
 
 def main():
     log = Messenger()
+
+    os.environ.setdefault("HOSTNAME", socket.gethostname())
     try:
         parser = ArgumentParser()
         add_options(parser)
diff --git a/dotbot/executor/linker.py b/dotbot/executor/linker.py
index f0e94bc..729c7a1 100644
--- a/dotbot/executor/linker.py
+++ b/dotbot/executor/linker.py
@@ -107,7 +107,7 @@ class Linker(Executor):
         Returns true if successfully linked files.
         '''
         success = False
-        source = os.path.join(self._base_directory, source)
+        source = os.path.expandvars(os.path.join(self._base_directory, source))
         if (not self._exists(link_name) and self._is_link(link_name) and
                 self._link_destination(link_name) != source):
             self._log.warning('Invalid link %s -> %s' %