diff --git a/.rubocop_todo.yml b/.rubocop_todo.yml
index 4c81012cd..627a5a51a 100644
--- a/.rubocop_todo.yml
+++ b/.rubocop_todo.yml
@@ -1,6 +1,6 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2018-12-06 21:06:59 -0500 using RuboCop version 0.51.0.
+# on 2018-12-20 21:38:24 +0000 using RuboCop version 0.51.0.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
@@ -38,13 +38,13 @@ Metrics/BlockLength:
 # Offense count: 9
 # Configuration parameters: CountComments.
 Metrics/ClassLength:
-  Max: 288
+  Max: 295
 
 # Offense count: 31
 Metrics/CyclomaticComplexity:
   Max: 14
 
-# Offense count: 1227
+# Offense count: 1234
 # Configuration parameters: AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
 # URISchemes: http, https
 Metrics/LineLength:
@@ -55,7 +55,7 @@ Metrics/LineLength:
 Metrics/MethodLength:
   Max: 33
 
-# Offense count: 11
+# Offense count: 12
 # Configuration parameters: CountComments.
 Metrics/ModuleLength:
   Max: 220
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ffbdac6ed..6fcf57a14 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,11 +5,11 @@
 * Your contribution here.
 * [#1850](https://github.com/ruby-grape/grape/pull/1850): Adds `same_as` validator - [@glaucocustodio](https://github.com/glaucocustodio).
 * [#1833](https://github.com/ruby-grape/grape/pull/1833): Allows to set the `ParamBuilder` globally - [@myxoh](https://github.com/myxoh).
-* [#1844](https://github.com/ruby-grape/grape/pull/1844): Fix: enforce `:tempfile` to be a `Tempfile` object in `File` validator - [@Nyangawa](https://github.com/Nyangawa).
 
 #### Fixes
 
-* Your contribution here.
+* [#1852](https://github.com/ruby-grape/grape/pull/1852): `allow_blank` called after `as` when the original param is not blank - [@glaucocustodio](https://github.com/glaucocustodio).
+* [#1844](https://github.com/ruby-grape/grape/pull/1844): Enforce `:tempfile` to be a `Tempfile` object in `File` validator - [@Nyangawa](https://github.com/Nyangawa).
 
 ### 1.2.2 (2018/12/07)
 
diff --git a/lib/grape/endpoint.rb b/lib/grape/endpoint.rb
index 5100f9654..650c53203 100644
--- a/lib/grape/endpoint.rb
+++ b/lib/grape/endpoint.rb
@@ -258,6 +258,7 @@ def run
         else
           run_filters before_validations, :before_validation
           run_validators validations, request
+          remove_aliased_params
           run_filters after_validations, :after_validation
           response_object = @block ? @block.call(self) : nil
         end
@@ -319,7 +320,14 @@ def build_helpers
       Module.new { helpers.each { |mod_to_include| include mod_to_include } }
     end
 
-    private :build_stack, :build_helpers
+    def remove_aliased_params
+      return unless route_setting(:aliased_params)
+      route_setting(:aliased_params).flat_map(&:keys).each do |aliased_param|
+        @params.delete(aliased_param)
+      end
+    end
+
+    private :build_stack, :build_helpers, :remove_aliased_params
 
     def helpers
       lazy_initialize! && @helpers
diff --git a/lib/grape/validations/validators/as.rb b/lib/grape/validations/validators/as.rb
index d1840539b..7547c8edd 100644
--- a/lib/grape/validations/validators/as.rb
+++ b/lib/grape/validations/validators/as.rb
@@ -8,7 +8,6 @@ def initialize(attrs, options, required, scope, opts = {})
 
       def validate_param!(attr_name, params)
         params[@alias] = params[attr_name]
-        params.delete(attr_name)
       end
     end
   end
diff --git a/spec/grape/validations/params_scope_spec.rb b/spec/grape/validations/params_scope_spec.rb
index 10b21db61..12865b8bc 100644
--- a/spec/grape/validations/params_scope_spec.rb
+++ b/spec/grape/validations/params_scope_spec.rb
@@ -155,6 +155,16 @@ def initialize(value)
       expect(last_response.status).to eq(400)
       expect(last_response.body).to eq('foo is empty')
     end
+
+    it do
+      subject.params do
+        requires :foo, as: :bar, allow_blank: false
+      end
+      subject.get('/alias-not-blank-with-value') {}
+      get '/alias-not-blank-with-value', foo: 'any'
+
+      expect(last_response.status).to eq(200)
+    end
   end
 
   context 'array without coerce type explicitly given' do