diff --git a/src/test/recovery/t/018_wal_optimize.pl b/src/test/recovery/t/018_wal_optimize.pl
index c39998bb2a..1bc01b5fa5 100644
--- a/src/test/recovery/t/018_wal_optimize.pl
+++ b/src/test/recovery/t/018_wal_optimize.pl
@@ -124,6 +124,7 @@ wal_skip_threshold = 0
 		$copy_file, qq(20000,30000
 20001,30001
 20002,30002));
+	$copy_file = TestLib::perl2host($copy_file);
 
 	# Test truncation with inserted tuples using both INSERT and COPY.  Tuples
 	# inserted after the truncation should be seen.