diff --git a/Gemfile b/Gemfile
index f93cb74e..de35cfee 100644
--- a/Gemfile
+++ b/Gemfile
@@ -7,8 +7,6 @@ source "https://rubygems.org"
 #  gemspec
 #end
 
-gem "prism", ">= 1.0.0"
-
 group :development do
   gem "rake"
   gem "stackprof", platforms: :mri
diff --git a/typeprof.gemspec b/typeprof.gemspec
index b21183ca..99c3864f 100644
--- a/typeprof.gemspec
+++ b/typeprof.gemspec
@@ -29,4 +29,5 @@ Gem::Specification.new do |spec|
   spec.require_paths = ["lib"]
 
   spec.add_runtime_dependency "rbs", ">= 3.6.0"
+  spec.add_runtime_dependency "prism", ">= 1.0.0"
 end