diff --git a/README.md b/README.md
index e0b60c1b6142df26f92dfac5c017d754570b4ac9..1521acd3a78165da3024bfd9a7bd55a073548052 100644
--- a/README.md
+++ b/README.md
@@ -130,15 +130,6 @@ The default config locations are `./config/brakeman.yml`, `~/.brakeman/config.ym
 
 The `-c` option can be used to specify a configuration file to use.
 
-# For Slim Users
-
-[Slim v3.0.0](https://github.com/slim-template/slim/blob/master/CHANGES#L12) dropped support for Ruby 1.8.7. Install a version of [`slim`](http://slim-lang.com/) compatible with your Ruby.
-
-| Ruby Version |       `Gemfile`       |              Command Line              |
-|--------------|-----------------------|----------------------------------------|
-| Ruby 1.8.7   | `gem 'slim', '< 3.0'` | `$ gem install slim --version '< 3.0'` |
-| Ruby 1.9+    | `gem 'slim'`          | `$ gem install slim`                   |
-
 # Continuous Integration
 
 There is a [plugin available](http://brakemanscanner.org/docs/jenkins/) for Jenkins/Hudson.
diff --git a/brakeman-min.gemspec b/brakeman-min.gemspec
index 5fe6672f1379a5114a372bb4bc1bbfb28cc5a841..f7c7232dd5b03117a0f08839030a376ad63a5296 100644
--- a/brakeman-min.gemspec
+++ b/brakeman-min.gemspec
@@ -16,6 +16,6 @@ Gem::Specification.new do |s|
   s.signing_key = gem_priv_key if File.exist? gem_priv_key and $0 =~ /gem\z/
   s.add_development_dependency "test-unit"
   s.add_dependency "ruby_parser", "~>3.7.0"
-  s.add_dependency "ruby2ruby", "~>2.1.1"
+  s.add_dependency "ruby2ruby", ">=2.1.1", "<2.3.0"
   s.add_dependency "multi_json", "~>1.2"
 end
diff --git a/brakeman.gemspec b/brakeman.gemspec
index 926ef40cd98bdb9afd2c298831f0d88919bc915b..a4385148382231e8da5af8db5c92341869293462 100644
--- a/brakeman.gemspec
+++ b/brakeman.gemspec
@@ -16,12 +16,13 @@ Gem::Specification.new do |s|
   s.signing_key = gem_priv_key if File.exist? gem_priv_key and $0 =~ /gem\z/
   s.add_development_dependency "test-unit"
   s.add_dependency "ruby_parser", "~>3.7.0"
-  s.add_dependency "ruby2ruby", "~>2.1.1"
+  s.add_dependency "ruby2ruby", ">=2.1.1", "<2.3.0"
   s.add_dependency "terminal-table", "~>1.4.5"
   s.add_dependency "fastercsv", "~>1.5"
-  s.add_dependency "highline", "~>1.6.20"
+  s.add_dependency "highline", "~>1.6"
   s.add_dependency "erubis", "~>2.6"
   s.add_dependency "haml", ">=3.0", "<5.0"
   s.add_dependency "sass", "~>3.0"
+  s.add_dependency "slim", ">=1.3.6", "<4.0"
   s.add_dependency "multi_json", "~>1.2"
 end