diff --git a/Gemfile b/Gemfile
index dffa567d..5afbd372 100644
--- a/Gemfile
+++ b/Gemfile
@@ -5,6 +5,6 @@ gemspec
 gem("minitest", "5.20.0")
 gem("rake-compiler", "1.2.5")
 gem("rake-compiler-dock", "1.3.1")
-gem("rdoc", "6.5.0")
+gem("rdoc", "6.6.0")
 
 gem("ruby_memcheck", "2.2.1") if Gem::Platform.local.os == "linux"