diff --git a/contrib/diff-highlight/DiffHighlight.pm b/contrib/diff-highlight/DiffHighlight.pm
index 536754583b..7440aa1c46 100644
--- a/contrib/diff-highlight/DiffHighlight.pm
+++ b/contrib/diff-highlight/DiffHighlight.pm
@@ -4,6 +4,11 @@ package DiffHighlight;
 use warnings FATAL => 'all';
 use strict;
 
+# Use the correct value for both UNIX and Windows (/dev/null vs nul)
+use File::Spec;
+
+my $NULL = File::Spec->devnull();
+
 # Highlight by reversing foreground and background. You could do
 # other things like bold or underline if you prefer.
 my @OLD_HIGHLIGHT = (
@@ -134,7 +139,7 @@ sub highlight_stdin {
 # fallback, which means we will work even if git can't be run.
 sub color_config {
 	my ($key, $default) = @_;
-	my $s = `git config --get-color $key 2>/dev/null`;
+	my $s = `git config --get-color $key 2>$NULL`;
 	return length($s) ? $s : $default;
 }