diff --git a/Gemfile b/Gemfile
index 47521a0..f3845c0 100644
--- a/Gemfile
+++ b/Gemfile
@@ -1,4 +1,4 @@
-source "http://rubygems.org"
+source "https://rubygems.org"
 
 # Specify your gem's dependencies in active_pdftk.gemspec
 gemspec
diff --git a/Gemfile.lock b/Gemfile.lock
index 5123043..876e2d4 100644
--- a/Gemfile.lock
+++ b/Gemfile.lock
@@ -5,7 +5,7 @@ PATH
       builder (>= 2.1.2)
 
 GEM
-  remote: http://rubygems.org/
+  remote: https://rubygems.org/
   specs:
     builder (3.0.0)
     diff-lcs (1.1.2)