diff --git a/docs/userguide/platforms/cmd_install.rst b/docs/userguide/platforms/cmd_install.rst
index 64298e01..c43c3123 100644
--- a/docs/userguide/platforms/cmd_install.rst
+++ b/docs/userguide/platforms/cmd_install.rst
@@ -48,7 +48,7 @@ Local
 PlatformIO supports installing development platform from local directory. Here
 is supported form:
 
-* file:///local/path/to/the/platform/dir
+* ``file:///local/path/to/the/platform/dir``
 
 VCS
 ~~~
diff --git a/platformio/managers/platform.py b/platformio/managers/platform.py
index 649166ef..c27a66ec 100644
--- a/platformio/managers/platform.py
+++ b/platformio/managers/platform.py
@@ -416,7 +416,9 @@ class PlatformBase(PlatformPackagesMixin, PlatformRunMixin):
         else:
             if id_ not in self._BOARDS_CACHE:
                 for boards_dir in bdirs:
-                    manifest_path = join(bdirs, "%s.json" % id_)
+                    if not isdir(boards_dir):
+                        continue
+                    manifest_path = join(boards_dir, "%s.json" % id_)
                     if not isfile(manifest_path):
                         continue
                     _append_board(id_, manifest_path)