diff --git a/HISTORY.rst b/HISTORY.rst
index f9f1ccc3..5ac2772b 100644
--- a/HISTORY.rst
+++ b/HISTORY.rst
@@ -6,6 +6,11 @@ Release Notes
 PlatformIO 4.0
 --------------
 
+4.0.4 (2019-??-??)
+~~~~~~~~~~~~~~~~~~
+
+* Fixed an issue with project generator for `CLion IDE <http://docs.platformio.org/page/ide/clion.html>`__ when 2 environments were used (`issue #2824 <https://github.com/platformio/platformio-core/issues/2824>`_)
+
 4.0.3 (2019-08-30)
 ~~~~~~~~~~~~~~~~~~
 
diff --git a/platformio/ide/tpls/clion/CMakeListsPrivate.txt.tpl b/platformio/ide/tpls/clion/CMakeListsPrivate.txt.tpl
index f96163fb..40f31e09 100644
--- a/platformio/ide/tpls/clion/CMakeListsPrivate.txt.tpl
+++ b/platformio/ide/tpls/clion/CMakeListsPrivate.txt.tpl
@@ -57,7 +57,7 @@ if (CMAKE_BUILD_TYPE MATCHES "{{ env_name }}")
 %end
 endif()
 
-% leftover_envs = set(envs) ^ set([env_name])
+% leftover_envs = list(set(envs) ^ set([env_name]))
 %
 % ide_data = {}
 % if leftover_envs:
diff --git a/platformio/project/helpers.py b/platformio/project/helpers.py
index 7ead95eb..9de1dbe2 100644
--- a/platformio/project/helpers.py
+++ b/platformio/project/helpers.py
@@ -194,10 +194,11 @@ def compute_project_checksum(config):
     return checksum.hexdigest()
 
 
-def load_project_ide_data(project_dir, envs):
+def load_project_ide_data(project_dir, env_or_envs):
     from platformio.commands.run import cli as cmd_run
-    assert envs
-    if not isinstance(envs, (list, tuple, set)):
+    assert env_or_envs
+    envs = env_or_envs
+    if not isinstance(envs, list):
         envs = [envs]
     args = ["--project-dir", project_dir, "--target", "idedata"]
     for env in envs:
@@ -217,6 +218,6 @@ def load_project_ide_data(project_dir, envs):
             _data = json.loads(line)
             if "env_name" in _data:
                 data[_data['env_name']] = _data
-    if len(envs) == 1 and envs[0] in data:
-        return data[envs[0]]
+    if not isinstance(env_or_envs, list) and env_or_envs in data:
+        return data[env_or_envs]
     return data or None