diff --git a/ref-filter.c b/ref-filter.c
index 5de616befe..3116f74225 100644
--- a/ref-filter.c
+++ b/ref-filter.c
@@ -976,7 +976,7 @@ static const char *copy_name(const char *buf)
 		if (!strncmp(cp, " <", 2))
 			return xmemdupz(buf, cp - buf);
 	}
-	return "";
+	return xstrdup("");
 }
 
 static const char *copy_email(const char *buf)
@@ -984,10 +984,10 @@ static const char *copy_email(const char *buf)
 	const char *email = strchr(buf, '<');
 	const char *eoemail;
 	if (!email)
-		return "";
+		return xstrdup("");
 	eoemail = strchr(email, '>');
 	if (!eoemail)
-		return "";
+		return xstrdup("");
 	return xmemdupz(email, eoemail + 1 - email);
 }
 
diff --git a/t/t6300-for-each-ref.sh b/t/t6300-for-each-ref.sh
index 97bfbee6e8..dc1c2e3152 100755
--- a/t/t6300-for-each-ref.sh
+++ b/t/t6300-for-each-ref.sh
@@ -485,6 +485,25 @@ test_expect_success 'Check ambiguous head and tag refs II (loose)' '
 	test_cmp expected actual
 '
 
+test_expect_success 'create tag without tagger' '
+	git tag -a -m "Broken tag" taggerless &&
+	git tag -f taggerless $(git cat-file tag taggerless |
+		sed -e "/^tagger /d" |
+		git hash-object --stdin -w -t tag)
+'
+
+test_atom refs/tags/taggerless type 'commit'
+test_atom refs/tags/taggerless tag 'taggerless'
+test_atom refs/tags/taggerless tagger ''
+test_atom refs/tags/taggerless taggername ''
+test_atom refs/tags/taggerless taggeremail ''
+test_atom refs/tags/taggerless taggerdate ''
+test_atom refs/tags/taggerless committer ''
+test_atom refs/tags/taggerless committername ''
+test_atom refs/tags/taggerless committeremail ''
+test_atom refs/tags/taggerless committerdate ''
+test_atom refs/tags/taggerless subject 'Broken tag'
+
 test_expect_success 'an unusual tag with an incomplete line' '
 
 	git tag -m "bogo" bogo &&