diff --git a/core/src/main/java/org/jruby/ext/zlib/JZlibRubyGzipWriter.java b/core/src/main/java/org/jruby/ext/zlib/JZlibRubyGzipWriter.java
index f2234d3e9833..174cd3937701 100644
--- a/core/src/main/java/org/jruby/ext/zlib/JZlibRubyGzipWriter.java
+++ b/core/src/main/java/org/jruby/ext/zlib/JZlibRubyGzipWriter.java
@@ -134,8 +134,9 @@ private int processLevel(int argc, IRubyObject[] args, Ruby runtime) {
         return level;
     }
 
-    private IRubyObject initializeCommon(IRubyObject stream, int level) {
-        realIo = (RubyObject) stream;
+    private IRubyObject initializeCommon(ThreadContext context, IRubyObject stream, int level) {
+        Ruby runtime = context.runtime;
+        realIo = stream;
         try {
             // the 15+16 here is copied from a Deflater default constructor
             Deflater deflater = new Deflater(level, 15+16, false);
@@ -158,9 +159,15 @@ public void write(byte[] bytes, int off, int len) throws IOException {
             };
 
             io = new GZIPOutputStream(ioOutputStream, deflater, 512, false);
+
+            // set mtime to current time in case it is never updated
+            long now = System.currentTimeMillis();
+            this.mtime = RubyTime.newTime(runtime, now);
+            io.setModifiedTime(now / 1000);
+
             return this;
         } catch (IOException ioe) {
-            throw getRuntime().newIOErrorFromException(ioe);
+            throw runtime.newIOErrorFromException(ioe);
         }
     }