diff --git a/lib/rdoc/generator/json_index.rb b/lib/rdoc/generator/json_index.rb
index 9d6f0d4356..5318b4cc57 100644
--- a/lib/rdoc/generator/json_index.rb
+++ b/lib/rdoc/generator/json_index.rb
@@ -1,5 +1,8 @@
 require 'json'
-require 'zlib'
+begin
+  require 'zlib'
+rescue LoadError
+end
 
 ##
 # The JsonIndex generator is designed to complement an HTML generator and
@@ -157,6 +160,8 @@ class RDoc::Generator::JsonIndex
   # Compress the search_index.js file using gzip
 
   def generate_gzipped
+    return unless defined?(Zlib)
+
     debug_msg "Compressing generated JSON index"
     out_dir = @base_dir + @options.op_dir
 
diff --git a/test/rdoc/test_rdoc_generator_json_index.rb b/test/rdoc/test_rdoc_generator_json_index.rb
index 06a5ddcd4a..9283fd9b76 100644
--- a/test/rdoc/test_rdoc_generator_json_index.rb
+++ b/test/rdoc/test_rdoc_generator_json_index.rb
@@ -137,7 +137,11 @@ class TestRDocGeneratorJsonIndex < RDoc::TestCase
   end
 
   def test_generate_gzipped
-    require 'zlib'
+    begin
+      require 'zlib'
+    rescue LoadError
+      skip "no zlib"
+    end
     @g.generate
     @g.generate_gzipped