diff --git a/HISTORY.rst b/HISTORY.rst
index ca81838c..25b3928c 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -1,6 +1,11 @@
 Release History
 ===============
 
+0.10.2 (2015-01-?)
+------------------
+
+* Fixed an issue with ``--json-output`` (`issue #42 <https://github.com/ivankravets/platformio/issues/42>`_)
+
 0.10.1 (2015-01-02)
 -------------------
 
diff --git a/platformio/commands/lib.py b/platformio/commands/lib.py
index f3b87445..96b750e5 100644
--- a/platformio/commands/lib.py
+++ b/platformio/commands/lib.py
@@ -1,12 +1,15 @@
 # Copyright (C) Ivan Kravets <me@ikravets.com>
 # See LICENSE for details.
 
+import json
+
 import click
 
 from platformio import app, exception
 from platformio.libmanager import LibraryManager
 from platformio.util import get_api_result, get_lib_dir
 
+
 LIBLIST_TPL = ("[{id:^14}] {name:<25} {compatibility:<30} "
                "\"{authornames}\": {description}")
 
@@ -160,7 +163,7 @@ def lib_list(json_output):
     items = lm.get_installed().values()
 
     if json_output:
-        click.echo(items)
+        click.echo(json.dumps(items))
         return
 
     if not items:
diff --git a/platformio/commands/list.py b/platformio/commands/list.py
index 3520d2ad..c47a95b8 100644
--- a/platformio/commands/list.py
+++ b/platformio/commands/list.py
@@ -1,6 +1,8 @@
 # Copyright (C) Ivan Kravets <me@ikravets.com>
 # See LICENSE for details.
 
+import json
+
 import click
 
 from platformio.platforms.base import PlatformFactory
@@ -23,7 +25,7 @@ def cli(json_output):
         })
 
     if json_output:
-        click.echo(data)
+        click.echo(json.dumps(data))
     else:
         for item in data:
             click.echo("{name:<20} with packages: {pkgs}".format(
diff --git a/platformio/commands/serialports.py b/platformio/commands/serialports.py
index d62d9482..c52f27da 100644
--- a/platformio/commands/serialports.py
+++ b/platformio/commands/serialports.py
@@ -1,6 +1,7 @@
 # Copyright (C) Ivan Kravets <me@ikravets.com>
 # See LICENSE for details.
 
+import json
 import sys
 
 import click
@@ -19,7 +20,7 @@ def cli():
 def serialports_list(json_output):
 
     if json_output:
-        click.echo(get_serialports())
+        click.echo(json.dumps(get_serialports()))
         return
 
     for item in get_serialports():