1 files changed, 3 insertions, 0 deletions

diff --git a/t/README b/t/README
index 593d4a4e27..b98bc563aa 100644
--- a/t/README
+++ b/t/README
@@ -439,6 +439,9 @@ and "sha256".
 GIT_TEST_WRITE_REV_INDEX=<boolean>, when true enables the
 'pack.writeReverseIndex' setting.
 
+GIT_TEST_SPARSE_INDEX=<boolean>, when true enables index writes to use the
+sparse-index format by default.
+
 Naming Tests
 ------------