diff --git a/flask/helpers.py b/flask/helpers.py
index e633e1b9..f714a699 100644
--- a/flask/helpers.py
+++ b/flask/helpers.py
@@ -616,17 +616,29 @@ def get_root_path(import_name):
 
     Not to be confused with the package path returned by :func:`find_package`.
     """
+    # Module already imported and has a file attribute.  Use that first.
+    mod = sys.modules.get(import_name)
+    if mod is not None and hasattr(mod, '__file__'):
+        return os.path.dirname(os.path.abspath(mod.__file__))
+
+    # Next attempt: check the loader.
     loader = pkgutil.get_loader(import_name)
+
+    # Loader does not exist or we're referring to an unloaded main module
+    # or a main module without path (interactive sessions), go with the
+    # current working directory.
     if loader is None or import_name == '__main__':
-        # import name is not found, or interactive/main module
         return os.getcwd()
+
     # For .egg, zipimporter does not have get_filename until Python 2.7.
+    # Some other loaders might exhibit the same behavior.
     if hasattr(loader, 'get_filename'):
         filepath = loader.get_filename(import_name)
     else:
         # Fall back to imports.
         __import__(import_name)
         filepath = sys.modules[import_name].__file__
+
     # filepath is import_name.py for a module, or __init__.py for a package.
     return os.path.dirname(os.path.abspath(filepath))