diff --git a/Gemfile b/Gemfile
index 27e6f60d..cdf72462 100644
--- a/Gemfile
+++ b/Gemfile
@@ -4,6 +4,10 @@ source "https://rubygems.org"
 
 gemspec
 
+gem "digest"
+gem "strscan"
+gem "base64"
+
 gem "rake"
 gem "rdoc"
 gem "test-unit"
diff --git a/net-imap.gemspec b/net-imap.gemspec
index 2f590cad..1bf3c74f 100644
--- a/net-imap.gemspec
+++ b/net-imap.gemspec
@@ -35,7 +35,4 @@ Gem::Specification.new do |spec|
 
   spec.add_dependency "net-protocol"
   spec.add_dependency "date"
-
-  spec.add_development_dependency "digest"
-  spec.add_development_dependency "strscan"
 end