diff --git a/Lib/pkgutil.py b/Lib/pkgutil.py
index e37ad45..014d86b 100644
--- a/Lib/pkgutil.py
+++ b/Lib/pkgutil.py
@@ -142,7 +142,7 @@ def _iter_file_finder_modules(importer, prefix=''):
     if importer.path is None or not os.path.isdir(importer.path):
         return
 
-    yielded = {}
+    yielded = set()
     import inspect
     try:
         filenames = os.listdir(importer.path)
@@ -152,31 +152,37 @@ def _iter_file_finder_modules(importer, prefix=''):
     filenames.sort()  # handle packages before same-named modules
 
     for fn in filenames:
-        modname = inspect.getmodulename(fn)
-        if modname=='__init__' or modname in yielded:
-            continue
-
         path = os.path.join(importer.path, fn)
-        ispkg = False
+        modname = inspect.getmodulename(fn)
 
-        if not modname and os.path.isdir(path) and '.' not in fn:
-            modname = fn
+        if modname:
+            if modname == '__init__'  or '.' in modname or modname in yielded:
+                continue
+            if os.path.isdir(path):
+                continue
+            ispkg = False
+        elif '.' not in fn and os.path.isdir(path):
             try:
                 dircontents = os.listdir(path)
             except OSError:
                 # ignore unreadable directories like import does
                 dircontents = []
-            for fn in dircontents:
-                subname = inspect.getmodulename(fn)
-                if subname=='__init__':
+            for subfn in dircontents:
+                subname = inspect.getmodulename(subfn)
+                if subname == '__init__': # and os.path.isfile(
+                    # os.path.join(path, subfn)
+                    # ):
+                    modname = fn
                     ispkg = True
                     break
             else:
                 continue    # not a package
+        else:
+            continue
+
+        yielded.add(modname)
+        yield prefix + modname, ispkg
 
-        if modname and '.' not in modname:
-            yielded[modname] = 1
-            yield prefix + modname, ispkg
 
 iter_importer_modules.register(
     importlib.machinery.FileFinder, _iter_file_finder_modules)
@@ -222,44 +228,7 @@ class ImpImporter:
         return ImpLoader(fullname, file, filename, etc)
 
     def iter_modules(self, prefix=''):
-        if self.path is None or not os.path.isdir(self.path):
-            return
-
-        yielded = {}
-        import inspect
-        try:
-            filenames = os.listdir(self.path)
-        except OSError:
-            # ignore unreadable directories like import does
-            filenames = []
-        filenames.sort()  # handle packages before same-named modules
-
-        for fn in filenames:
-            modname = inspect.getmodulename(fn)
-            if modname=='__init__' or modname in yielded:
-                continue
-
-            path = os.path.join(self.path, fn)
-            ispkg = False
-
-            if not modname and os.path.isdir(path) and '.' not in fn:
-                modname = fn
-                try:
-                    dircontents = os.listdir(path)
-                except OSError:
-                    # ignore unreadable directories like import does
-                    dircontents = []
-                for fn in dircontents:
-                    subname = inspect.getmodulename(fn)
-                    if subname=='__init__':
-                        ispkg = True
-                        break
-                else:
-                    continue    # not a package
-
-            if modname and '.' not in modname:
-                yielded[modname] = 1
-                yield prefix + modname, ispkg
+        yield from _iter_file_finder_modules(self, prefix)
 
 
 class ImpLoader: