diff --git a/t/t8005-blame-i18n.sh b/t/t8005-blame-i18n.sh
index 847d098c0..75da219ed 100755
--- a/t/t8005-blame-i18n.sh
+++ b/t/t8005-blame-i18n.sh
@@ -33,11 +33,15 @@ author $SJIS_NAME
 summary $SJIS_MSG
 EOF
 
+filter_author_summary () {
+	sed -n -e '/^author /p' -e '/^summary /p' "$@"
+}
+
 test_expect_success !MINGW \
 	'blame respects i18n.commitencoding' '
-	git blame --incremental file | \
-		egrep "^(author|summary) " > actual &&
-	test_cmp actual expected
+	git blame --incremental file >output &&
+	filter_author_summary output >actual &&
+	test_cmp expected actual
 '
 
 cat >expected <<EOF
@@ -52,9 +56,9 @@ EOF
 test_expect_success !MINGW \
 	'blame respects i18n.logoutputencoding' '
 	git config i18n.logoutputencoding eucJP &&
-	git blame --incremental file | \
-		egrep "^(author|summary) " > actual &&
-	test_cmp actual expected
+	git blame --incremental file >output &&
+	filter_author_summary output >actual &&
+	test_cmp expected actual
 '
 
 cat >expected <<EOF
@@ -68,9 +72,9 @@ EOF
 
 test_expect_success !MINGW \
 	'blame respects --encoding=UTF-8' '
-	git blame --incremental --encoding=UTF-8 file | \
-		egrep "^(author|summary) " > actual &&
-	test_cmp actual expected
+	git blame --incremental --encoding=UTF-8 file >output &&
+	filter_author_summary output >actual &&
+	test_cmp expected actual
 '
 
 cat >expected <<EOF
@@ -84,9 +88,9 @@ EOF
 
 test_expect_success !MINGW \
 	'blame respects --encoding=none' '
-	git blame --incremental --encoding=none file | \
-		egrep "^(author|summary) " > actual &&
-	test_cmp actual expected
+	git blame --incremental --encoding=none file >output &&
+	filter_author_summary output >actual &&
+	test_cmp expected actual
 '
 
 test_done