diff --git a/spec/onyx-rest/action_spec.cr b/spec/onyx-rest/action_spec.cr
index 9c04f9d..b8f1e2d 100644
--- a/spec/onyx-rest/action_spec.cr
+++ b/spec/onyx-rest/action_spec.cr
@@ -57,7 +57,7 @@ class JSONAction
 
   params do
     json require: true, any_content_type: true do
-      type user do
+      type user, nilable: true do
         type name : String
         type email : String
       end
@@ -65,7 +65,7 @@ class JSONAction
   end
 
   def call
-    context.response << "#{params.json.user.name}, #{params.json.user.email}"
+    context.response << "#{params.json.user.try &.name}, #{params.json.user.try &.email}"
   end
 end
 
@@ -120,6 +120,26 @@ describe Onyx::REST::Action do
     end
 
     context "JSON action" do
+      context "with empty JSON" do
+        it do
+          response = client.post("/json",
+            body: "{}"
+          )
+          response.status_code.should eq 200
+          response.body.should eq ", "
+        end
+      end
+
+      context "with empty user" do
+        it do
+          response = client.post("/json",
+            body: %Q[{"user": null}]
+          )
+          response.status_code.should eq 200
+          response.body.should eq ", "
+        end
+      end
+
       it do
         response = client.post("/json",
           body: %Q[{"user": {"name": "John", "email": "foo@example.com"}}]
diff --git a/src/onyx-rest/endpoint/params/form.cr b/src/onyx-rest/endpoint/params/form.cr
index defd367..2c2e249 100644
--- a/src/onyx-rest/endpoint/params/form.cr
+++ b/src/onyx-rest/endpoint/params/form.cr
@@ -93,7 +93,7 @@ module Onyx::REST::Endpoint
       include ::HTTP::Params::Serializable
 
       {% verbatim do %}
-        macro type(argument, **options, &block)
+        macro type(argument, nilable = false, **options, &block)
           {% if block %}
             {% unless options.empty? %}
               @[::HTTP::Param({{**options}})]
@@ -102,9 +102,9 @@ module Onyx::REST::Endpoint
             {% if argument.is_a?(Path) %}
               {% raise "Cannot declare namespaced nested query parameter" if argument.names.size > 1 %}
 
-              getter {{argument.names.first.underscore}} : {{argument.names.first.camelcase.id}}
+              getter {{argument.names.first.underscore}} : {{argument.names.first.camelcase.id}}{{" | Nil".id if nilable}}
             {% elsif argument.is_a?(Call) %}
-              getter {{argument.name.underscore}} : {{argument.name.camelcase.id}}
+              getter {{argument.name.underscore}} : {{argument.name.camelcase.id}}{{" | Nil".id if nilable}}
             {% else %}
               {% raise "BUG: Unhandled argument type #{argument.class_name}" %}
             {% end %}
diff --git a/src/onyx-rest/endpoint/params/json.cr b/src/onyx-rest/endpoint/params/json.cr
index b492596..5839112 100644
--- a/src/onyx-rest/endpoint/params/json.cr
+++ b/src/onyx-rest/endpoint/params/json.cr
@@ -87,7 +87,7 @@ module Onyx::REST::Endpoint
       include JSON::Serializable
 
       {% verbatim do %}
-        macro type(argument, **options, &block)
+        macro type(argument, nilable = false, **options, &block)
           {% if block %}
             {% unless options.empty? %}
               @[JSON::Field({{**options}})]
@@ -96,9 +96,9 @@ module Onyx::REST::Endpoint
             {% if argument.is_a?(Path) %}
               {% raise "Cannot declare namespaced nested query parameter" if argument.names.size > 1 %}
 
-              getter {{argument.names.first.underscore}} : {{argument.names.first.camelcase.id}}
+              getter {{argument.names.first.underscore}} : {{argument.names.first.camelcase.id}}{{" | Nil".id if nilable}}
             {% elsif argument.is_a?(Call) %}
-              getter {{argument.name.underscore}} : {{argument.name.camelcase.id}}
+              getter {{argument.name.underscore}} : {{argument.name.camelcase.id}}{{" | Nil".id if nilable}}
             {% else %}
               {% raise "BUG: Unhandled argument type #{argument.class_name}" %}
             {% end %}
diff --git a/src/onyx-rest/endpoint/params/query.cr b/src/onyx-rest/endpoint/params/query.cr
index efb1a29..1f31011 100644
--- a/src/onyx-rest/endpoint/params/query.cr
+++ b/src/onyx-rest/endpoint/params/query.cr
@@ -42,7 +42,7 @@ module Onyx::REST::Endpoint
       include ::HTTP::Params::Serializable
 
       {% verbatim do %}
-        macro type(argument, **options, &block)
+        macro type(argument, nilable = false, **options, &block)
           {% if block %}
             {% unless options.empty? %}
               @[::HTTP::Param({{**options}})]
@@ -51,9 +51,9 @@ module Onyx::REST::Endpoint
             {% if argument.is_a?(Path) %}
               {% raise "Cannot declare namespaced nested query parameter" if argument.names.size > 1 %}
 
-              getter {{argument.names.first.underscore}} : {{argument.names.first.camelcase.id}}
+              getter {{argument.names.first.underscore}} : {{argument.names.first.camelcase.id}}{{" | Nil".id if nilable}}
             {% elsif argument.is_a?(Call) %}
-              getter {{argument.name.underscore}} : {{argument.name.camelcase.id}}
+              getter {{argument.name.underscore}} : {{argument.name.camelcase.id}}{{" | Nil".id if nilable}}
             {% else %}
               {% raise "BUG: Unhandled argument type #{argument.class_name}" %}
             {% end %}