diff --git a/src/java.base/share/classes/java/util/zip/GZIPOutputStream.java b/src/java.base/share/classes/java/util/zip/GZIPOutputStream.java
index d3880c2f4d7..cea0880fca6 100644
--- a/src/java.base/share/classes/java/util/zip/GZIPOutputStream.java
+++ b/src/java.base/share/classes/java/util/zip/GZIPOutputStream.java
@@ -212,7 +212,9 @@ public class GZIPOutputStream extends DeflaterOutputStream {
      */
     private void writeTrailer(byte[] buf, int offset) throws IOException {
         writeInt((int)crc.getValue(), buf, offset); // CRC-32 of uncompr. data
-        writeInt(def.getTotalIn(), buf, offset + 4); // Number of uncompr. bytes
+        // RFC 1952: Size of the original (uncompressed) input data modulo 2^32
+        int iSize = (int) def.getBytesRead();
+        writeInt(iSize, buf, offset + 4);
     }
 
     /*