diff --git a/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/LogFileCompressor.java b/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/LogFileCompressor.java
index 2e45fc5..1eb83dc 100644
--- a/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/LogFileCompressor.java
+++ b/gerrit-pgm/src/main/java/com/google/gerrit/pgm/util/LogFileCompressor.java
@@ -127,6 +127,7 @@
         } finally {
           out.close();
         }
+        tmp.setReadOnly();
       } finally {
         in.close();
       }