diff --git a/lib/Tuba/Converter.pm b/lib/Tuba/Converter.pm
index 360ec1e8..6ddfedf4 100644
--- a/lib/Tuba/Converter.pm
+++ b/lib/Tuba/Converter.pm
@@ -103,7 +103,7 @@ sub output {
         logger->info("Input ($fp) : ".file($fp)->slurp);
         if ($ENV{HARNESS_ACTIVE}) {
             print STDERR "# diagnostics --start---:\n";
-            print STDERR "# Errors running $cmd :\n ".join '',<$errs>;
+            print STDERR "# Errors running $cmd :\n ".file("$errs")->slurp;
             print STDERR "# errors $@" if $@;
             print STDERR "# Input ($fp) : ".file($fp)->slurp;
             print STDERR "rapper version : ".`rapper --version`;