diff --git a/pyproject.toml b/pyproject.toml
index d926ffa4..6db278ea 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [project]
 name = "spectree"
-version = "1.2.7"
+version = "1.2.8"
 dynamic = []
 description = "generate OpenAPI document and validate request&response with Python annotations."
 readme = "README.md"
diff --git a/spectree/plugins/falcon_plugin.py b/spectree/plugins/falcon_plugin.py
index 063190c6..2b68fe37 100644
--- a/spectree/plugins/falcon_plugin.py
+++ b/spectree/plugins/falcon_plugin.py
@@ -223,7 +223,7 @@ def validate(
 
         before(_req, _resp, req_validation_error, _self)
         if req_validation_error:
-            return
+            return None
 
         result = func(*args, **kwargs)
 
@@ -243,6 +243,8 @@ def validate(
 
         after(_req, _resp, resp_validation_error, _self)
 
+        # `falcon` doesn't use this return value. However, some users may have
+        # their own processing logics that depend on this return value.
         return result
 
     @staticmethod
@@ -325,7 +327,7 @@ async def validate(
 
         before(_req, _resp, req_validation_error, _self)
         if req_validation_error:
-            return
+            return None
 
         result = (
             await func(*args, **kwargs)