diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index f13ef4d..560cc13 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -2519,6 +2519,9 @@ gzfile_free(void *p)
 	}
 	zstream_finalize(z);
     }
+    if (gz->ec) {
+	rb_econv_close(gz->ec);
+    }
     xfree(gz);
 }
 
diff --git a/test/zlib/test_zlib.rb b/test/zlib/test_zlib.rb
index e1ecbf8..4feddab 100644
--- a/test/zlib/test_zlib.rb
+++ b/test/zlib/test_zlib.rb
@@ -1732,6 +1732,16 @@ def test_gunzip_no_memory_leak
       };
     end
 
+    def test_gzip_reader_encoding_conversion_no_memory_leak
+      assert_no_memory_leak(%W[-r#{LOADED_ZLIB} -rstringio], "#{<<~"{#"}", "#{<<~'};'}", rss: true)
+      d = Zlib.gzip("data")
+      opts = {external_encoding: "Shift_JIS", internal_encoding: "UTF-8"}
+      10_000.times {Zlib::GzipReader.new(StringIO.new(d), **opts).close}
+      {#
+        20_000.times {Zlib::GzipReader.new(StringIO.new(d), **opts).close}
+      };
+    end
+
     # Test for signal interrupt bug: Z_BUF_ERROR with avail_out > 0
     # This reproduces the issue where thread wakeup during GzipReader operations
     # can cause Z_BUF_ERROR to be raised incorrectly