diff --git a/CHANGELOG.md b/CHANGELOG.md
index 3acda6b8a..af986974c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,10 @@
   [CocoaPods#2696](https://github.com/CocoaPods/CocoaPods/issues/2696)
   [CocoaPods#2625](https://github.com/CocoaPods/CocoaPods/issues/2625)
 
+* Fixes an issue linting the `flatten` for http sources in a podspec.  
+  [Eloy Durán](https://github.com/alloy)
+  [Core#193](https://github.com/CocoaPods/Core/issues/193)
+
 
 ## 0.34.4
 
diff --git a/lib/cocoapods-core/specification/dsl.rb b/lib/cocoapods-core/specification/dsl.rb
index 1e3a16765..4ac4f37dc 100644
--- a/lib/cocoapods-core/specification/dsl.rb
+++ b/lib/cocoapods-core/specification/dsl.rb
@@ -232,10 +232,10 @@ module DSL
       # The keys accepted by the hash of the source attribute.
       #
       SOURCE_KEYS = {
-        :git => [:tag, :branch, :commit, :submodules],
-        :svn => [:folder, :tag, :revision],
-        :hg => [:revision],
-        :http => [:type, :sha256, :sha1],
+        :git  => [:tag, :branch, :commit, :submodules].freeze,
+        :svn  => [:folder, :tag, :revision].freeze,
+        :hg   => [:revision].freeze,
+        :http => [:flatten, :type, :sha256, :sha1].freeze,
         :path => nil,
       }.freeze