diff --git a/mitogen/master.py b/mitogen/master.py
index 2783cc57..a11edb49 100644
--- a/mitogen/master.py
+++ b/mitogen/master.py
@@ -62,7 +62,8 @@ def _stdlib_paths():
     ]
     prefixes = (getattr(sys, a) for a in attr_candidates if hasattr(sys, a))
     version = 'python%s.%s' % sys.version_info[0:2]
-    return set(os.path.join(p, 'lib', version) for p in prefixes)
+    return set(os.path.abspath(os.path.join(p, 'lib', version))
+               for p in prefixes)
 
 
 def get_child_modules(path):
@@ -283,7 +284,7 @@ class ModuleFinder(object):
             return False
 
         # six installs crap with no __file__
-        modpath = getattr(module, '__file__', '')
+        modpath = os.path.abspath(getattr(module, '__file__', ''))
         if 'site-packages' in modpath:
             return False
 
@@ -535,10 +536,10 @@ class ModuleResponder(object):
         stream.sent_modules.add(fullname)
 
     def _on_get_module(self, msg):
-        LOG.debug('%r.get_module(%r)', self, msg)
         if msg == mitogen.core._DEAD:
             return
 
+        LOG.debug('%r._on_get_module(%r)', self, msg.data)
         stream = self._router.stream_by_id(msg.src_id)
         fullname = msg.data
         if fullname in stream.sent_modules:
diff --git a/mitogen/parent.py b/mitogen/parent.py
index ddf9b14a..bd659fde 100644
--- a/mitogen/parent.py
+++ b/mitogen/parent.py
@@ -532,13 +532,10 @@ class ModuleForwarder(object):
         tup = self.importer._cache[fullname]
         if tup is not None:
             for related in tup[4]:
-                LOG.debug('%r._on_get_module(): trying related %r',
-                          self, related)
-                try:
-                    rtup = self.importer._cache[related]
-                except KeyError:
-                    LOG.debug('%r._on_get_module(): skipping %r, not in cache', 
-                             self, related)
+                rtup = self.importer._cache.get(related)
+                if not rtup:
+                    LOG.debug('%r._on_get_module(): skipping absent %r',
+                               self, related)
                     continue
                 self._send_one_module(msg, rtup)