diff --git a/t/t3400-rebase.sh b/t/t3400-rebase.sh
index 71b1735e1d..0643d01525 100755
--- a/t/t3400-rebase.sh
+++ b/t/t3400-rebase.sh
@@ -18,10 +18,7 @@ GIT_AUTHOR_EMAIL=bogus@email@address
 export GIT_AUTHOR_NAME GIT_AUTHOR_EMAIL
 
 test_expect_success 'prepare repository with topic branches' '
-	git config core.logAllRefUpdates true &&
-	echo First >A &&
-	git update-index --add A &&
-	git commit -m "Add A." &&
+	test_commit "Add A." A First First &&
 	git checkout -b force-3way &&
 	echo Dummy >Y &&
 	git update-index --add Y &&
@@ -32,9 +29,7 @@ test_expect_success 'prepare repository with topic branches' '
 	git mv A D/A &&
 	git commit -m "Move A." &&
 	git checkout -b my-topic-branch main &&
-	echo Second >B &&
-	git update-index --add B &&
-	git commit -m "Add B." &&
+	test_commit "Add B." B Second Second &&
 	git checkout -f main &&
 	echo Third >>A &&
 	git update-index A &&