diff --git a/AUTHORS b/AUTHORS
index 8cc6824cd..e966139be 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -44,6 +44,7 @@ David Mohr
 David Vierra
 Diego Russo
 Dmitry Dygalo
+Duncan Betts
 Edison Gustavo Muenz
 Edoardo Batini
 Eduardo Schettino
diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index f97ff3787..40797c30c 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -1,7 +1,7 @@
 3.0.5.dev0
 ==========
 
-*
+* Add hint to error message hinting possible missing __init__.py (`#478`_). Thanks `@DuncanBetts`_.
 
 * An error message is now displayed if ``--confcutdir`` is not a valid directory, avoiding
   subtle bugs (`#2078`_).
@@ -20,8 +20,10 @@
 *
 
 .. _@adler-j: https://github.com/adler-j
+.. _@DuncanBetts: https://github.com/DuncanBetts
 .. _@nedbat: https://github.com/nedbat
 
+.. _#478: https://github.com/pytest-dev/pytest/issues/478
 .. _#2038: https://github.com/pytest-dev/pytest/issues/2038
 .. _#2078: https://github.com/pytest-dev/pytest/issues/2078
 .. _#2082: https://github.com/pytest-dev/pytest/issues/2082
diff --git a/_pytest/main.py b/_pytest/main.py
index 5771a1699..dd0775501 100644
--- a/_pytest/main.py
+++ b/_pytest/main.py
@@ -704,10 +704,9 @@ class Session(FSCollector):
         path = self.config.invocation_dir.join(relpath, abs=True)
         if not path.check():
             if self.config.option.pyargs:
-                msg = "file or package not found: "
+                raise pytest.UsageError("file or package not found: " + arg + " (missing __init__.py?)")
             else:
-                msg = "file not found: "
-            raise pytest.UsageError(msg + arg)
+                raise pytest.UsageError("file not found: " + arg)
         parts[0] = path
         return parts